U.S. patent application number 12/899350 was filed with the patent office on 2011-05-12 for ultrasonic hairstyling device.
This patent application is currently assigned to Goody Products, Inc.. Invention is credited to Roy Attride, Leo F. Costello, JR., Nathan Wang, Christopher Ryan Yahnker.
Application Number | 20110108051 12/899350 |
Document ID | / |
Family ID | 43973213 |
Filed Date | 2011-05-12 |
United States Patent
Application |
20110108051 |
Kind Code |
A1 |
Yahnker; Christopher Ryan ;
et al. |
May 12, 2011 |
Ultrasonic Hairstyling Device
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.
Inventors: |
Yahnker; Christopher Ryan;
(Raleigh, NC) ; Costello, JR.; Leo F.; (Raleigh,
NC) ; Wang; Nathan; (Raleigh, NC) ; Attride;
Roy; (Raleigh, NC) |
Assignee: |
Goody Products, Inc.
Atlanta
GA
|
Family ID: |
43973213 |
Appl. No.: |
12/899350 |
Filed: |
October 6, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
61249074 |
Oct 6, 2009 |
|
|
|
61255657 |
Oct 28, 2009 |
|
|
|
Current U.S.
Class: |
132/229 ;
132/269 |
Current CPC
Class: |
A45D 1/04 20130101; A45D
2200/207 20130101 |
Class at
Publication: |
132/229 ;
132/269 |
International
Class: |
A45D 1/04 20060101
A45D001/04; A45D 1/14 20060101 A45D001/14 |
Claims
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 of claim 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 of claim 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 of claim 1, wherein the ultrasonic transducer
includes a horn in contact with the barrel.
5. The device of claim 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 of claim 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 of claim 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 of claim 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 of claim 7, wherein the ultrasonic transducer
includes a horn in contact with the elongate housing.
11. The device of claim 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 of claim 11, wherein the barrel has a length equal
to a wavelength of the ultrasonic vibrations or a multiple of the
wavelength.
13. The device of claim 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 of claim 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 of claim 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 of claim 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 of claim 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.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] 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
[0002] 1. Field of the Disclosure
[0003] The present disclosure is generally directed to hairstyling
devices, and more particularly to curling irons and flat irons.
[0004] 2. Description of Related Art
[0005] 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.
[0006] 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
[0007] 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.
[0008] 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.
[0009] 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.
[0010] 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.
[0011] 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.
[0012] 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.
[0013] 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.
[0014] 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.
[0015] 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
[0016] 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.
[0017] FIG. 1 is a perspective, cutaway view of an exemplary
curling iron constructed in accordance with one or more aspects of
the disclosure.
[0018] FIG. 2 is a perspective, end view of the curling iron of
FIG. 1 to depict an exemplary ultrasonic transducer in greater
detail.
[0019] FIG. 3 is a perspective view of the ultrasonic transducer of
FIG. 2 to depict one or more aspects of the disclosure relating to
embodiments having a Langevin transducer configuration.
[0020] FIG. 4 is a cross-sectional view of a housing of the curling
iron shown in FIGS. 1 and 2 taken along the lines 4-4 of FIG. 2 to
depict the mounting of the ultrasonic transducer of FIGS. 1-3
within the housing in an axial orientation and barrel position in
accordance with several aspects of the disclosure.
[0021] FIG. 5 is a schematic diagram of an exemplary drive circuit
for controlling the operation of the ultrasonic transducer of FIGS.
2-4.
[0022] FIG. 6 is a perspective, cutaway view of an exemplary flat
iron constructed in accordance with one or more aspects of the
disclosure.
[0023] FIG. 7 is a perspective, partial view of an arm of an
exemplary flat iron constructed in accordance with another
embodiment.
[0024] FIG. 8 is a perspective view of an exemplary ultrasonic
transducer of the flat irons of FIGS. 6 and 7.
[0025] FIG. 9 is a cross-sectional view of an arm of a flat iron
similar to the view shown in FIG. 4 to depict an exemplary mounting
of the ultrasonic transducer of FIG. 8 within the arm.
[0026] FIG. 10 is a schematic diagram of another exemplary drive
circuit for controlling the operation of the ultrasonic transducers
of the disclosed hairstyling devices.
[0027] FIGS. 11A and 11B are graphical diagrams of data collected
during energy transmission testing of the disclosed hairstyling
devices.
[0028] 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.
[0029] 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
[0030] 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.degree. F., use of the disclosed devices has
effectively styled hair at temperature levels around about
250.degree. F. to about 350.degree. F.
[0031] 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.
[0032] 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.
[0033] Turning to the drawing figures, FIG. 1 depicts a curling
iron 20 having an elongate housing 22. A base portion of the
housing 22 forms a handle 24 from which a barrel 26 of the housing
22 extends. The handle 24 provides a handle grip surface 28 for an
operator of the curling iron 20 to grasp during use. The barrel 26
provides a styling surface 30 spaced from the handle grip surface
28 to avoid or minimize unwanted user contact with the styling
surface 30. The styling surface 30 is generally configured for
winding hair to be styled around the barrel 26 to form curls or
other styling effects. To that end, the elongate housing 22 and
each portion thereof may be generally cylindrically shaped,
although the handle 24 and the barrel 26 may be shaped otherwise
and, moreover, need not be similarly shaped. The handle 24 and the
barrel 26 are configured such that the housing 22 is shaped as a
wand or an arm.
[0034] The handle 24 and the barrel 26 may be integrally formed to
any desired extent. The handle 24, for instance, may include a
rubberized, plastic, or other grip (not shown) mounted upon an
extension of the barrel 26. In other cases, one or both of the
portions of the elongate housing 22 may be formed via interlocking
or interconnected half- or other shells. For example, the handle 24
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 the
handle 24 may be constructed of a variety of materials other than
plastics, including stainless steel. The barrel 26 may include one
or more components constructed of stainless steel, iron, aluminum,
or other thermally conductive materials. In some cases, the handle
24 and the barrel 26 are discrete structures connected to one
another via one or more fasteners, one or more snap-fit connectors,
or some other coupling mechanism. Alternatively, the handle 24 may
be configured as a sleeve that fits over a tube or other housing
that runs the length of the device to also form the barrel 26.
[0035] The handle 24 includes a number of user interface or control
elements. To this end, the handle 24 may have a non-circular
cross-sectional shape. The example shown, for instance, has a
longitudinal ridge 31 that runs the entire length of the handle 24.
The ridge 31 presents a panel or other section of the grip surface
28 for the user interface or control elements. The ridge 31 and
other projections may also improve the grip surface 28. In other
cases, the handle 24 may have an oval or other non-circular
cross-sectional shape to configure the grip surface 28 in a desired
manner. Similarly, the barrel 26 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.
[0036] Both the handle 24 and the barrel 26 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 curling iron 20, which includes
ultrasonic vibration as described below. In this example, the
handle 24 houses a circuit board 32 shaped as an elongate strip
oriented lengthwise and mounted within the handle 24 via one or
more screw or other fasteners. The barrel 26, in turn, houses one
or more heating elements 34 and an ultrasonic transducer 36. The
heating elements 34 are generally disposed within the barrel 26 in
thermal communication with the styling surface 30 to transfer heat
to the hair wound around the barrel 26. In this example, each
heating element 34 includes a thermally conductive strip 38
disposed and extending along an interior wall of the barrel 26.
Each strip 38 may have any desired shape, including, for instance,
a flat or curved plate. Both the heating elements 34 and the
ultrasonic transducer 36 are generally oriented lengthwise within
the barrel 26.
[0037] Each heating element 34 may be conventionally constructed
and configured. Suitable heating element materials include ceramics
and metals. In this example, each heating element 34 includes an
elongate, flat, ceramic plate disposed upon a flat or other mount
inside the barrel 26. Each mount may be constructed of a heat
conductive material to encourage the transfer of heat from the
heating element 34 to the styling surface 30 of the barrel 26. The
barrel 26 in this case has a pair of opposing heating elements
positioned lengthwise within the barrel 26. Each heating element 34
may run the length of the barrel 26 or any desired segment thereof.
In this example, each heating element 34 extends from an inner end
of the barrel 26 to the electronic transducer 36, stopping short of
the outer end of the barrel 26 as shown. Any number of heating
elements 34 may be disposed within the barrel 26 at a variety of
locations, including those that reach the outer end of the barrel
26 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 the heating elements 34
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
curling iron 20, 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.
[0038] The curling iron 20 also includes a clip assembly 40
pivotally secured to the elongate housing 22. The clip assembly 40
may include one or more springs or other elastic elements to bias
the clip assembly 40 toward the barrel 26 to thereby clamp and hold
the hair in position between the styling surface 30 of the barrel
26 and a plate 42 of the clip assembly 40. The plate 42 extends
lengthwise along the barrel 26 and has a styling surface 44 on an
inward facing side. The plate 42 is generally capable of moving the
styling surface 44 into a position facing or opposite from the
styling surface 30 of the barrel 26. The barrel 26 and the plate 42
may be configured so that the shapes of the styling surfaces 30 and
44 are matching or complementary. For instance, the plate 42 may be
curved to an extent to match the curvature of the barrel 26.
[0039] In this example, the plate 42 is pivotally coupled to the
elongate housing 22 via a pivot link 46 of the clip assembly 40.
The pivot link 46 has one or more ends that terminate at a
respective pivot joint or hinge 48 at which the clip assembly 40 is
secured to the elongate housing 22. In this example, the clip
assembly 40 has two diametrically opposed pivot joints 48 at an
inner or proximate end 50 of the barrel 26. Each pivot joint 48
includes a pin, bolt, or other pivot element 52 that passes through
the pivot link 46 and the barrel 26. The pivot link 46 generally
extends laterally outward from the barrel 26 to form a lever 54,
which may, in turn, include a grip surface 56 to facilitate
operator engagement during operation. The manner in which the clip
assembly 40 is pivotally coupled may vary considerably. For
instance, in some cases, the clip assembly 40 is secured to the
handle 24.
[0040] The shape, construction, and other characteristics of the
handle 24, the barrel 26, and the clip assembly 40 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.
[0041] The circuit board 32 includes a number of circuit elements
58 to control each heating element 34 and the ultrasonic transducer
36. 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 the elongate housing 22 to handle one of the two functions
alone. In any event, the circuit elements 58 may be disposed in a
location within the elongate housing 22 (e.g., near a base end of
the handle 24) to avoid the heat generated by the heating elements
34. Because one or more of the circuit elements 58 may also
constitute sources of heat, the circuit elements 58 may be
nonetheless configured for operation in an elevated temperature
environment. Temperature levels within the housing 22 may exceed
normal operating temperatures even though the circuit elements 58
are spaced from the heating elements 34. To help dissipate heat,
one or more of the circuit elements 58 may include a heat sink 60.
For example, one or more copper elements may be disposed upon a
circuit board 32 or a respective one of the circuit elements 58. In
some cases, the curling iron 20 may include a barrier, divider,
wall, or other element within the housing 22 to block the
transmission of heat from the barrel 26 to the components within
the handle 24.
[0042] The circuit board 32 is coupled to a power source via a
power cord 62. In other examples, the circuit board 32 is coupled
to a battery or other portable power source, which may be
rechargeable via, for instance, the power cord 62. The circuit
board 32 is also coupled to one or more control or input elements
64. One or more of the control elements 64 may be directed to
activating and deactivating the curling iron 20 or one or more
operational features thereof, including ultrasonic vibration. Other
control elements 64 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 curling iron 20 for personal use
requirements or preferences.
[0043] The positioning, structural configuration, and other
physical characteristics of the electrical and circuit-related
components of the curling iron 20 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.
[0044] As described below, the ultrasonic transducer 36 is
generally configured to generate ultrasonic vibrations to improve
and facilitate hairstyling through lower levels of applied heat. In
this example, the ultrasonic transducer 36 includes an assembly of
components disposed within the barrel 26. In that way, the
vibrations generated by the transducer 36 are transmitted through
the barrel 26 to the styling surface 30, at which point the
vibrations are, in turn, transmitted to the hair in contact
therewith. To that end, the ultrasonic transducer 36 is generally
disposed in a position that allows the vibrations to be transmitted
to the styling surface 30 and, ultimately, to the hair being
styled. In this example, the transducer 36 is mounted or oriented
lengthwise along a longitudinal axis of the barrel 26. The
longitudinal axes of the barrel 26 and the transducer 36 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 the transducer 36 to be
maximized in the limited space available within the barrel 26.
However, as shown with the examples described below, the location
and orientation of the transducer 36 may vary, including, for
instance, non-axial orientation involving a radial mount.
[0045] With reference now to a FIG. 2, a partial view of the
curling iron 20 is shown to depict one possible location of the
ultrasonic transducer in greater detail. In this example, the
ultrasonic transducer 36 is disposed adjacent an end cap or plug 66
of the barrel 26. The transducer 36 is shown in phantom to depict
how a front face 68 of the ultrasonic transducer 36 is in contact
with the end cap 66. To this end, the transducer 36 is positioned
at an outer or distal end 69 of the barrel 26 such that the front
face 68 abuts the end cap 66. As described further below, the
transducer 36 is also positioned, shaped and sized for further
contact with the barrel 26. Generally speaking, the width of the
transducer 36 may result in contact with the longitudinal wall(s)
of the barrel 26. In this case, the transducer 36 is configured
such that an inner longitudinal wall of the barrel 26 is contacted
by a rim 70 of the transducer 36 to form an annular interface at
the front face 68. In this way, the vibrations generated by the
transducer 36 may be transmitted to the styling surface 30 via both
the end cap 66 and the annular interface with the barrel 26. As
also shown in FIG. 3, the rim 70 extends along the longitudinal
axis of the transducer 36 to form a cylindrical surface or band for
the annular interface with the barrel 26.
[0046] The ultrasonic transducer 36 may be disposed at other
locations within the elongate housing 22. For example, the
transducer 36 may be disposed at the inner end 50 of the barrel 26.
In that case, the front face 68 of the transducer 36 may again be
adjacent another end cap or other face (not shown) to maximize the
surface area of the interface between the transducer 36 and the
barrel 26. In such cases, the transducer 36 may not extend the
entire width of the barrel 26 so as to allow electrical connections
and other elements to pass by the transducer 36 to reach the
heating elements 34 (FIG. 1). To that end, the rim 70 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 the transducer 36 is disposed not
at either end of the barrel 26, but rather at a point therebetween,
the contact between the rim 70 and the inner surface of the barrel
26 may form the only transmission conduit between the barrel 26 and
the transducer 36 for the ultrasonic vibrations. Still other cases
may position the transducer 36 within the handle 24, at a wall or
other element separating the handle 24 and the barrel 26, or at any
other location within the housing 22.
[0047] The ultrasonic transducer 36 may be secured within the
elongate housing 22 via an adhesive layer or film 72 between the
rim 70 and the inner surface of the barrel 26 (also shown in FIG.
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 the barrel 26. The 3M adhesive products may be
configured as a pressure-sensitive film. The adhesive material is
generally insensitive to the elevated heat levels within the barrel
26. The material from 3M Corporation is rated for use at up to 550
F degrees. The adhesive layer 72 generally addresses the challenge
of securing the transducer 36 without dampening or otherwise
interfering with the transmission of the ultrasonic vibrations. To
that end, the adhesive layer 72 may be configured and applied as a
thin film. In some cases, the ultrasonic transducer 36 is
alternatively or additionally inserted into the barrel 26 or, more
generally, the elongate housing 22 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 the transducer 36 and the styling surface 30.
Furthermore, an adhesive layer need not be applied between the
transducer 36 and the end cap 66, thereby allowing the vibrations
to pass through that interface without adhesive-related
dissipation.
[0048] FIG. 3 shows the ultrasonic transducer 36 in greater detail.
The transducer 36 generally includes a horn 80, a piezoelectric
section 82, and a reflector 84. In this example, these stages of
the transducer 36 are arranged in the Langevin configuration. The
horn 80 is generally configured as a front-end stage to transmit
the ultrasonic vibrations generated in the piezoelectric section
82. To that end, the horn 80 is shaped and otherwise configured for
efficient transfer and transmission of the vibrations. In this
example, the horn 80 is shaped as a truncated cone (or frustum)
such that a tapered section of increasing diameter extends forward
from the piezoelectric section 82. The horn 80 terminates in a
front face 86, which may be flat to maximize contact with the end
cap 66, the barrel 26 (FIG. 1) or other component of the housing
22. The reflector 84 is positioned behind the piezoelectric section
82 as a back-end stage of the transducer 36 generally designed to
reflect or direct the ultrasonic vibrations in the desired
transmission direction through the front end stage (e.g., through
the front face 86 of the horn 80 toward the barrel 26 or the
housing 22). The reflector 84 is sized and weighted to that end.
For example, a solid cylinder of stainless steel or other dense
material may be used as the reflector 84. The reflector 84 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 the piezoelectric section 82.
[0049] The piezoelectric section 82 is disposed between the front-
and back-end stages of the transducer 36. The piezoelectric section
82 includes a set of piezoelectric discs 88 arranged in a stack.
Each disc 88 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 the heating
elements 34 are conventionally raised to temperature levels of
approximately 400-450.degree. F. for hairstyling (or
250-350.degree. F. with the benefit of ultrasonic vibration as
described herein). The piezoelectric discs 88 as well as the
transducer 36 are commercially available from Sunnytec Electronics
Co. Ltd. (Taiwan). The disc stack is generally configured so that
the vibrations generated by the discs 88 are in phase for
constructive amplification. In this case, the stack includes four
discs 88 oriented axially, or longitudinally, within the housing 22
(FIG. 1). Other disc arrangements are possible, but an even number
of discs is useful for maintaining a constructive interference
scenario for the vibrations. Electrodes 90 are positioned on each
side of the discs 88 to apply an excitation or drive signal to each
disc 88. 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 of piezoelectric discs 88 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 the transducer 36. As a result, the
excitation signal frequency is generally selected in accordance
with the desired vibration frequency of the transducer 36.
[0050] Positive and negative pairs of the electrodes 90 are reached
via U-shaped contacts 92, which generally run along the stack
lengthwise before bending radially inward toward the electrodes 90.
Each contact 92, in turn, is connected to wiring (not shown) that
leads to the circuit board 32 (FIG. 1). The contacts 92 may be
integrally formed with the electrodes 90. More generally, each
contact 92 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 the transducer 36 within the housing 22 (FIG.
1).
[0051] The three stages of the transducer 36 are secured to one
another by a bolt or other fastener 94 that extends axially forward
from the reflector 84 through the discs 88 of the piezoelectric
stage 82 to reach the horn 80. To that end, each disc 88 and each
electrode 90 may have a hole (not shown) formed in the center
thereof to allow the bolt 94 to pass through. The bolt 94 may have
a threaded end 96 configured to engage a matching threaded opening
(not shown) in the horn 80. The bolt 94 may be welded or otherwise
fixed to the reflector 84 at its other end. In some cases, the bolt
94 may be integrally formed with the reflector 84. During assembly
of the transducer 36, the reflector 84 is rotated relative to the
horn 80 for compression of the stages of the transducer 36. The
horn 80 and the reflector 84 include opposed pairs of flattened
sections 98, 100, respectively, to allow a wrench or other tool to
help tighten the assembly to reach a suitable level of
compression.
[0052] FIG. 4 shows the exemplary axial mounting of the transducer
36 within the outer end 69 of the barrel 26 in greater detail. The
front face 68 of the horn 80 is disposed along, and in contact
with, the end cap 66 of the barrel 26. The rim 70 is sized so that
the annular interface and contact between the transducer 36 and the
barrel 26 spans the entire circumference of an inner surface 102 of
the barrel 26. In this case, the adhesive layer 72 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. The adhesive layer 72 may also be used
to secure the end cap 66 in place at the outer end 69 of the barrel
26. Additional mounting hardware (not shown) may be disposed within
the barrel 26 to hold the transducer 36 in place.
[0053] The heating elements 34 in this example are disposed along
the inner surface 102 of the barrel 26. However, the heating
elements 34 need not be curved to match the curvature of the barrel
26 and, thus, need not be disposed in contact with the inner
surface 102 across their entire width or length. Instead, the
heating elements 34 are more generally disposed along the barrel 26
at a radial position outward of the transducer 36 and either
directly or indirectly coupled to the inner surface 102. An
indirect coupling may include heat-conductive mounting hardware
(not shown) that establishes the transmission of heat from the
elements 34 to the inner surface 102 and, from there, through the
barrel 26 to the styling surface 30 opposite the inner surface
102.
[0054] The transducer 36 has an overall axial length L.sub.T and a
horn length L.sub.H, as defined in FIG. 4. Generally speaking,
these length dimensions are selected to maximize the generation and
transmission of ultrasonic vibrations through resonance of the
transducer 36. To that end, the dimensions L.sub.T and L.sub.H may
be about .lamda./2 and .lamda./4, respectively, where .lamda. is
the wavelength of the ultrasonic vibrations generated by the
transducer 36. When these length conditions are met (or
approximately met), the transducer 36 may be driven to an
oscillation mode having a node (where vibration amplitudes are at
or near a minimum) at a rear face 104 of the reflector 84 and an
anti-node (where vibration amplitudes are at or near a maximum) at
the front face 68 of the horn 80. Under these conditions, the
vibrations generated by the transducer 36 form standing waves
within the transducer 36, effectively reflecting from the
back-stage reflector 84 and combining in phase with those traveling
forward to the horn 80 to reach the front face 68 at peak strength.
In one example, the overall axial length L.sub.T is 56 mm and the
horn length L.sub.H is 17 mm.
[0055] Notwithstanding the foregoing, the diameter of the barrel 26
may present challenges for the design and mounting of the
transducer 36 and thereby cause a deviation from the ideal
.lamda./4 configuration. In some cases, the diameter of the rim 70
of the horn 80 may be limited by the diameter of the barrel 26. As
a result, the length of the horn 80 may be shorter than the optimal
length in order to achieve resonant operation with the other stages
of the transducer 36. In one example with a 1.5'' diameter barrel,
the horn 80 is shorter than the optimal length to ensure that the
horn 80 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.
[0056] With the horn-shaped (or frustoconical) transducer
configuration shown in FIGS. 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, the piezoelectric discs 88
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 the transducer assembly 36, 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.
[0057] During operation, the vibrations generated by the
piezoelectric discs 88 travel axially forward to the horn 80. Once
at the horn 80, the vibrations travel further forward to transmit
energy to the end cap 66 via the front face 68. The vibrations of
the horn 80 also spread radially to transfer energy to the barrel
26 via the annular interface between the rim 70 and the inner
surface 102 of the barrel. Through these transmission paths, the
ultrasonic energy eventually reaches the hair clamped between the
styling surface 30 and the styling surface 44 (FIG. 1). There, the
ultrasonic energy is applied to the moisture entrapped in the
medulla of the hair.
[0058] The transmission of ultrasonic energy improves the styling
of the hair by facilitating heat transfer within the barrel 26 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 the heating elements 34 to the hair through
excitation of the molecules within the barrel 26. The excitation of
the barrel molecules lowers the heat transfer resistance of the
barrel 26. More effective transmission of heat through the barrel
26 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 the barrel 26 other than the hot spots.
The general result is more uniform distribution of heat along the
barrel 26. 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.
[0059] With reference now to FIG. 5, an exemplary drive circuit 110
for the ultrasonic transducer 36 (FIGS. 1-4) includes several
components for controlling and generating the drive signal. The
circuit 110 as shown does not include any components for
controlling or powering the heating elements 34 (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 circuit
110 includes an EMI line filter 112, which is optional depending on
whether interference on the AC power line provided to the curling
iron 20 is considered a problem. In some cases, such interference
or other noise may affect the operation of the circuit 110 to an
extent that the drive signal includes harmonic or other undesired
frequency components. The operation of the curling iron 20 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 converter 114 and a low voltage
AC-to-DC converter 116. The high voltage converter 114 includes a
bridge rectifier 118 and capacitor C3 configured to generate a high
DC voltage input V_hv suitable for use in generating the drive
signal. The low voltage converter 116 includes a bridge rectifier
120 and a voltage regulating network 122 to generate an output
suitable for use as a power supply Vcc for the logic devices of the
circuit 110. In this case, the network 122 includes a Zener diode
D3 to lower the output of the bridge rectifier 120 and a regulator
124 to generate a stable power supply voltage Vcc of 12 Volts. The
regulator 124 may include one of the linear regulators commercially
available from National Semiconductor Corporation associated with
product number LM78L12.
[0060] The exemplary drive circuit 110 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 a timer 126 configured and set in
astable mode for use as an oscillator. To that end, the timer 126
is coupled to a resistor R12 to set the frequency and duty cycle
parameters. A commercially available timer suitable for use as the
timer 126 may be obtained from National Semiconductor Corporation
associated with product number LM555. The oscillating output of the
timer 126 may be provided to a divider 128 configured to, for
instance, reduce the duty cycle by 50%. A full-bridge driver 130
receives the oscillating signal to develop switch control signals
for two full-bridge switch circuit pairs 132. In operation, the
switch circuit pairs 132 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 the transducer 36
for generation of the ultrasonic vibrations.
[0061] 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 elements 34 (FIG. 1) as well as
the heat generated by the operation of the drive circuit 110 itself
may lead to temperatures within the housing 22 (FIG. 1) that would
otherwise be elevated to undesirable levels. That said, the
operation of the oscillator and other AC-related components of the
circuit 110 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.
[0062] In some cases, one or more circuit elements may be
incorporated into the drive circuit 110 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.
[0063] The drive signal generated by the circuit 110 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.
[0064] The drive circuit 110 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 in FIG. 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.
[0065] Turning to FIG. 6, the benefits of ultrasonic vibration are
now described in connection with another exemplary hairstyling
device. Like the curling iron 20 described above, a flat iron 140
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.
[0066] The flat iron 140 includes an elongate housing 142 that has
several components in common with the housing 22 described above.
The housing 142 similarly defines a handle grip surface 144 and a
styling surface 146 spaced from the handle grip surface 144. A
plate 148 is also pivotally coupled to the housing 142 to clamp the
hair between a styling surface 149 of the plate 148 and the styling
surface 146. In this case, however, the plate 148 is carried by
another elongate housing 150 (rather than a clip), and the styling
surface 146 is an exterior face of another plate 152 carried by the
housing 142. The housing 150 is configured as a pivoting arm (or
wand) with a proximal, linked end 154 upon which a pivot joint 156
is mounted for coupling with a proximal, linked end 158 of the
pivoting arm (or wand) of the housing 142. The two wands or arms
extend outward from the linked ends to define a longitudinal axis
of each housing 142, 150. The plates 148 and 152 are disposed at
distal, free ends 160 and 162 of the housing arms, respectively, at
locations disposing the styling surfaces 146, 149 opposite one
another. The housing 150 also has a handle grip surface 164 so that
an operator can grasp the two wand-shaped housings 142, 150 to
bring the styling surfaces 146, 149 toward one another. In this
manner, the plates 148, 152 can act as pressure plates to apply
pressure to the hair to be styled therebetween. The pivot joint 156
is spring-loaded to bias the flat iron 140 open when no inward
force is applied to the handle grip surfaces 144, 164.
[0067] Each plate 148, 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. Each housing 142,
150 may be made from stainless steel, aluminum, plastic, or any
other desired material.
[0068] The flat iron 140 also includes a power cord 166 for
delivery of power to one or more control circuits (not shown)
disposed within one or both of the housings 142, 150. In this case,
a control circuit may be disposed within the housing 142 in
proximity to a control panel 168 that includes user interface
elements 170, 172 for operator control of the flat iron 140. The
control panel 168 may be used to activate and deactivate an
ultrasonic vibration feature of the flat iron 140 provided by an
ultrasonic transducer 174. The control panel 168 may also be used
to select a temperature level or other operational parameters. Heat
is applied to the hair clamped between the styling surfaces 146,
149 via one or more heating elements 176 in thermal communication
with a respective one of the surfaces 146, 149. Each heating
element 176 may be configured as a flat plate secured to an
interior side of one of the plates 148, 152. In this case, the
housing 142 is shown with one of the heating elements 176,
although, in other cases, the other housing 150 may contain the
sole (or an additional) heating element secured to the plate
148.
[0069] The ultrasonic transducer 174 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. The transducer
174 is generally configured to generate ultrasonic vibrations to
facilitate energy transmission with one or both of the pressure
plates 148, 152 and to transfer vibration energy to the hair
clamped therebetween. However, in this case, the interior space
provided by each housing 142, 150 of the flat iron 140 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 the transducer 174
axially within the housing, with the longitudinal axes of the
transducer 174 and the housing aligned. Consequently, the
transducer 174 in the depicted example is configured with a horn
178 having an adapter that translates the longitudinal, axial
vibration into vibration in a lateral direction toward one of the
plate 152. To that end, the horn 178 includes an L- or elbow-shaped
head 180 that projects forward from a cylindrical section of the
horn 178 adjacent a piezoelectric stage 182. After extending
forward, the L-shaped head 180 projects laterally downward to place
an outer end 183 in contact with an interior surface 184 of the
plate 152. The remainder of the transducer 174 may rest upon, and
be secured to the heating element 176 or other surface or component
within the housing 142. A similarly mounted transducer may be
housed within the housing 150 for transmission of ultrasonic
vibrations through the plate 148. In operation, the vibration mode
causes the head 180 to move laterally (as opposed to axially)
toward and away from the plate 152. The transducer 174 thus
vibrates along a hammer-like motion path.
[0070] Despite the directional translation of the vibration
propagation achieved by the head 180, the profile of the flat iron
wands or arms may, in some cases, be too thin to mount the
transducer 174 within the housing. The thickness of the heating
element 176 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.
[0071] FIG. 7 depicts one optional solution in which a flat iron
wand or arm 190 has a main housing 192 and a transducer cover 194.
The main housing 192 may be configured in a similar manner to those
described above, with the exception of a hole on an outward facing
side 196 from which the transducer cover 194 flares or extends
laterally outward. In this way, the transducer cover 194 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 in FIG. 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 a plate 198. However,
with sufficient additional space under the cover 194, the
transducer may be mounted laterally with the front face of an
adapter-free Langevin horn in contact with the interior surface of
the plate 198, such that the longitudinal axis of the transducer is
orthogonal to the longitudinal axis of the main housing 192. Thus,
the main housing 192 and the transducer cover 194 may be shaped as
desired and, furthermore, be integrally formed to any desired
extent, including, for instance, as a unitary molded component.
[0072] With reference now to FIGS. 8 and 9, a Langevin transducer
200 with a vibration-translating horn adapter 202 is shown in
greater detail. Starting from a back end, the transducer 200 has a
reflector stage 204 in compression fit with a piezoelectric stage
206 and a horn stage 208. The reflector and piezoelectric stages
204, 206 may be configured in a manner similar to the example
described above. The horn stage 208 may have a cylindrical section
210 having an inner end 212 adjacent the piezoelectric stage 206
and an outer end 214 adjacent the horn adapter 202. The outer end
214 may have a flat face from which an axially oriented arm 216 of
the horn adapter 202 extends forward. The arm 216 may be integrally
formed with the cylindrical section 210 to any desired extent or,
alternatively, be attached to the cylindrical section 210 via a
variety of different attachment techniques (e.g., welding,
adhesive, etc.). The arm 216 projects outward until reaching a
corner or shoulder 218 of the adapter 202, at which point another
arm 220 projects laterally downward. The arms 216, 220 need not be
rectilinear as shown, and may be solid, hollow, or any combination
thereof.
[0073] As shown in FIG. 9, a bottom or downward facing surface 222
of the arm 220 is disposed in contact with an inner face 224 of a
styling plate 226. The face 224 is exposed for such contact between
a heating element 227 and an inward face 228 of a housing 230. The
horn adapter 202 may be secured to the inner face 224 via an
adhesive layer or film. Alternatively or additionally, the adapter
202 may be fixed to the plate 226 via welding or other attachment
techniques. In some cases, the horn adapter 202 is fixed in place
by mounting hardware that engages the housing 230 or the heating
element 227. For example, the mounting hardware may engage
electrode plates 232 of the piezoelectric stage 206. The adapter
202 may be optionally attached to an inner surface of the heating
element 227 or other component or surface within the housing
228.
[0074] The overall length L.sub.T and horn length L.sub.H
dimensions of the transducer 200 may be selected in accordance with
the above-described considerations. The horn length includes the
combined length of the cylindrical section 210 and the adapter 202.
The length of the reflector stage 204 is noted as L.sub.R and may
be a direct multiple of the wavelength in the interest of
constructive interference (as is the case with the above-described
example).
[0075] As described above, the transducer 200 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 .lamda./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.
[0076] Operation of the transducer configuration shown in FIGS. 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.
[0077] With reference now to FIG. 10, a drive circuit 240 is
configured for controlling the transducer of FIGS. 8 and 9. The
drive circuit 240 has several features in common with the drive
circuit described above and may, in fact, be used to control the
other transducers described herein. The drive circuit 240 is also
generally configured as a full H-bridge driver, albeit with
different circuit elements. For instance, the circuit 240 includes
a bridge rectifier 242 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 converter 244 for generation of a 15
Volt power supply, which, in turn, is fed to a regulator 246 that
develops a 5 Volt power supply used by an oscillator 248 and an
inverter 250. The oscillator 248 establishes the frequency of the
drive signal by passing its oscillating output to a pair of
full-bridge drivers 252, either directly or indirectly through the
inverter 250. Each driver 252 then sends switch control signals in
accordance with the oscillator frequency to a pair of switch
circuits 254, the terminals of which are connected across the
transducer discs in the full H-bridge configuration.
[0078] 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 with FIG. 1, the power
transmission increased about 14% when the ultrasonic vibrations
were applied. With the flat iron of FIG. 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.
[0079] FIG. 12 shows an ultrasonic curling iron 260 constructed in
accordance with another exemplary embodiment. The curling iron 260
may be similar to the curling iron described above with the
exception of the transducer and heating element locations. In this
case, an ultrasonic transducer 262 is disposed outside of a barrel
264. Even though the transducer 262 is not housed within the barrel
264, the transducer 262 is again disposed and oriented along the
longitudinal axis of the barrel 264. The transducer 262 is secured
to an exterior side 266 of an end cap 268 of the barrel 264 in any
desired manner. As described above, the transducer 262 may have a
horn with a flat front face to maximize the surface area in contact
with the exterior side 266 of the end cap 268. The transducer 262
may be housed within an enclosure 270 coupled to the barrel 264 via
one or more fasteners, an adhesive layer, or any other attachment
mechanism. This alternative location for the transducer 262 may
provide design flexibility if, in fact, space within the barrel 264
is too limited for a desired transducer configuration, size,
geometry, etc. The transducer 262 is shown schematically in FIG.
12, and need not have the Langevin transducer configuration shown.
Despite the alternative transducer location, the vibration
transmission path still passes through a styling surface 272 of the
barrel 264.
[0080] One advantage of this exterior mounting of the embodiment of
FIG. 12 is that the heating element(s) may run the entire length of
the barrel 264. With the transducer 262 not disposed within the
barrel 264, the transducer 262 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 a distal end 274 of the
barrel.
[0081] 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,
a transducer 280 includes a substantially frustoconical horn stage
282 extending forward from piezoelectric and reflector stages 284,
286. The horn stage 282 is generally shaped so that a contact
interface with a plate 288 disposed along the horn stage 282 is
formed. To that end, the horn stage 282 includes a pair of
diametrically opposed flat surfaces 290, each of which may have a
parabolic outline. The surfaces 290 may lie in parallel planes such
that, when the transducer 280 is oriented axially along the plate
288, one of the surfaces 290 lies flat against a top side of the
plate 288 to increase the contact surface area. To that end, an
opening 292 in a heating element 294 may provide access to the top
side of the plate 288. In other cases, the opening 292 may be cut
out to match the shape of the transducer surface.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] 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.
[0087] 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.
[0088] 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
[0089] 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.
[0090] 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.
[0091] 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.
* * * * *