U.S. patent application number 12/790217 was filed with the patent office on 2010-09-23 for oscillatory motors and devices incorporating them.
This patent application is currently assigned to ULTREO, INC.. Invention is credited to Richard K. Taylor.
Application Number | 20100237720 12/790217 |
Document ID | / |
Family ID | 42226888 |
Filed Date | 2010-09-23 |
United States Patent
Application |
20100237720 |
Kind Code |
A1 |
Taylor; Richard K. |
September 23, 2010 |
OSCILLATORY MOTORS AND DEVICES INCORPORATING THEM
Abstract
An oscillatory device incorporating a limited angle torque motor
capable of oscillating one or more end effector(s) is provided. The
device may additionally incorporate an ultrasound transducer and/or
a waveguide structure.
Inventors: |
Taylor; Richard K.; (Fall
City, WA) |
Correspondence
Address: |
SPECKMAN LAW GROUP PLLC
1201 THIRD AVENUE, SUITE 330
SEATTLE
WA
98101
US
|
Assignee: |
ULTREO, INC.
Seattle
WA
|
Family ID: |
42226888 |
Appl. No.: |
12/790217 |
Filed: |
May 28, 2010 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11777615 |
Jul 13, 2007 |
7732952 |
|
|
12790217 |
|
|
|
|
60807460 |
Jul 14, 2006 |
|
|
|
Current U.S.
Class: |
310/38 ; 318/139;
320/108 |
Current CPC
Class: |
H02K 11/33 20160101;
H02K 33/16 20130101; A61C 17/3481 20130101; H02K 1/12 20130101;
A61C 17/20 20130101 |
Class at
Publication: |
310/38 ; 318/139;
320/108 |
International
Class: |
H02K 33/02 20060101
H02K033/02; H02J 7/02 20060101 H02J007/02 |
Claims
1. An oscillatory motor comprising a rotor assembly, a drive shaft
mounted to move with the rotor assembly, a stator assembly, and a
centering mechanism, wherein the rotor assembly comprises a wound
wire rotor and the stator assembly incorporates at least one
multipole permanent magnet, whereby when the stator assembly is
energized, the rotor assembly and drive shaft are moved from a
neutral position through an arc or an angular displacement of less
than 180.degree. with respect to the stator assembly and the drive
shaft is returned to a neutral position by the centering
mechanism.
2. An oscillatory motor of claim 1, wherein the stator assembly
comprises an arced multipole permanent magnet.
3. An oscillatory motor of claim 1, wherein the stator assembly
comprises multipole permanent magnets mounted on plates spaced
apart to form at least one gap and the rotor assembly is positioned
in the at least one gap,
4. An oscillatory motor of claim 1, wherein the centering mechanism
is a spring.
5. An oscillatory motor of claim 1, wherein the centering mechanism
is a leaf spring.
6. An oscillatory motor of claim 1, wherein the centering mechanism
is mounted inside the magnetic rotor.
7. An oscillatory motor of claim 3, wherein the arc or angular
displacement of a drive portion of the drive shaft is less than
10.degree. in each direction from the neutral position.
8. An oscillatory device comprising: a handle housing a power
supply and an oscillatory motor having a rotor assembly, a drive
shaft mounted to move with the rotor assembly, a stator assembly,
and a centering mechanism, wherein the rotor assembly comprises a
wound wire rotor and the stator assembly incorporates at least one
multipole permanent magnet, whereby when the stator assembly is
energized, the rotor assembly and drive shaft move from a neutral
position through an arc or an angular displacement of less than
180.degree. and, when the stator assembly isn't energized, the
drive shaft is returned to the neutral position by the centering
mechanism.
9. An oscillatory device of claim 8, wherein the rotor assembly and
drive shaft are moved in opposite directions from the neutral
position when the polarity of the input current is changed.
10. An oscillatory device of claim 8, additionally comprising an
accessory adapted to be mechanically coupled to the drive shaft,
wherein the combination of the oscillatory motor and the accessory
form a resonant system during operation of the oscillatory
motor.
11. An oscillatory device of claim 10, wherein the resonant
frequency of the resonant system is between 20 Hz and 10,000
Hz.
12. An oscillatory device of claim 11, wherein resonant frequency
of the resonant system is greater than about 50 Hz and less than
about 500 Hz.
13. An oscillatory device of claim 8, wherein the stator assembly
comprises an arced multipole permanent magnet.
14. An oscillatory device of claim 8, wherein the stator assembly
comprises multipole permanent magnets mounted on plates spaced
apart to form at least one gap and the rotor assembly is positioned
in the at least one gap.
15. An oscillatory device of claim 8, wherein the centering
mechanism is a leaf spring.
16. An oscillatory device of claim 8, wherein the arc or angular
displacement of a drive portion of the drive shaft is less than
10.degree. in each direction from the neutral position.
17. An oscillatory device of claim 8, wherein the power supply is a
rechargeable battery mounted in the handle.
18. An oscillatory device of claim 17, wherein the rechargeable
battery is inductively chargeable, and a charge coil and a charge
core are additionally mounted in the handle.
19. An oscillatory device of claim 8, additionally comprising a
charger assembly including an inductive charger base for inductive
charging of the rechargeable battery, a cord detachably connectible
to the charger base at one end and connectible to an electrical
source by means of a plug at the other end.
20. An oscillatory device of claim 17, wherein the charger base
incorporates charging elements that permit inductive charging of
rechargeable batteries from multiple sources, including alternating
current sources and direct current sources.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation application of U.S.
patent application Ser. No. 11/777,615, filed Jul. 13, 2007 and
issued as U.S. Pat. No. 7,732,952 on Jun. 8, 2010, which claims
priority to U.S. Patent Application 60/807,460, filed Jul. 14,
2006. The disclosure of the parent application is incorporated by
reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Technical Field of the Invention
[0003] The present invention relates generally to the field of
oscillatory motors and devices incorporating them, such as portable
and hand-held oscillating devices for application as toothbrushes,
oral hygiene devices, personal healthcare devices, and the
like.
[0004] 2. Brief Description of Related Art
[0005] The use of handheld oscillating devices for personal
healthcare and oral hygiene applications such as power
toothbrushes, and the like, has increased significantly. Many power
toothbrushes employ a motor, generally located in the toothbrush
handle, to vibrate or oscillate a brush head and bristle tufts
located on a brush head. Other types of personal care and hygiene
devices, portable tools, and the like also employ a motor to
vibrate or oscillate a component or an accessory. The motors in
these devices may be powered, for example, by connection to an
electrical power source, by battery power, or by alternative power
sources, such as solar or other renewable power sources. Many
portable devices utilize rechargeable batteries.
[0006] Various types of drive motors may be used to produce
oscillation of a component or an accessory or an end effector at
"sonic" frequencies below about 1 MHz. A stepper motor may be used
to provide oscillating rotary motion of a motor drive shaft that
may be coupled to an end effector such as a toothbrush head.
Stepper motors are generally controllable to provide precise
manipulation of the amplitude of oscillation. Wobble weight motors,
conventional rotary motors, gear motors and piezoelectric motors or
actuators may alternatively be used as drive motors for producing
oscillations at sonic frequencies.
[0007] Limited angle torque actuators operate on the principal that
a force, or torque, is exerted on a current carrying conductor
placed in a magnetic field. The force is proportional to the
direction and magnitude of the current and the flux density field.
When a permanent magnet flux density field is fixed, the direction
of rotation depends on the polarity of the input current, and the
amount of torque produced is directly proportional to the magnitude
of the input current. Limited angle torque motors typically
incorporate a rotor comprising field magnets and a stator
supporting armature windings that are wound single phase, unlike
conventional brushless motors, which eliminates the need for
commutation circuitry. Armature windings may be embedded in slots
provided around the inner periphery of a laminated stator or,
alternatively, the armature may be toroidally wound on a slotless
stator. Limited angle torque actuators are generally used as
positioners for operating servovalves, mirrors, antennaes, and
other devices that require rotation through relatively small
angles.
[0008] Motors producing oscillatory motion for use in personal care
devices, such as oral hygiene devices and toothbrushes, typically
have relatively high mass and inertia drive requirements and
typically require higher torque capability than many otherwise
suitable motors provide. In addition, the (small) size, (low)
weight and (low) noise requirements for motors used in personal
care devices are difficult to satisfy. Oscillatory motors of the
present invention employing limited angle torque drivers are
designed to satisfy these requirements.
SUMMARY OF THE INVENTION
[0009] Devices that oscillate a component or an end effector at
sonic frequencies of less than 1 MHz and oscillatory motors
providing oscillation of components and end effectors at sonic
frequencies of less than 1 MHz are provided. The oscillatory motor
may be a limited angle torque actuator and generally drives an
output shaft through limited angular excursions of less than
180.degree.. The drive output, or angular excursion of an output
shaft of the oscillatory motor, may be a limited angular excursion
or rotation of an output shaft about its longitudinal axis, or it
may be a limited angular excursion of an output shaft in an arc.
The oscillatory limited angle torque motor of the present invention
preferably incorporates a return mechanism, such as a torsion
spring, that returns the output shaft to a neutral position
following each angular excursion.
[0010] The oscillatory device may be provided as a personal care
device or an oral hygiene device such as a power toothbrush, or
another device that oscillates a component or an end effector at
frequencies of less than 1 MHz. The oscillatory devices may have a
unitary construction with the working components integrated in a
generally unitary housing, or they may comprise multiple components
that are detachable from one another and may be mechanically
coupled to provide oscillation to a detachable component or
accessory. The oscillatory motors of the present invention may be
mounted in a handle component or in an accessory component.
[0011] In one embodiment, for example, the oscillatory device
comprises a personal care device, such as a power toothbrush or
another oral hygiene device having a handle and a detachable
accessory, such as a brush head, wherein the oscillatory motor is
mounted in the handle and an oscillatory drive shaft extends into a
coupled brush head to oscillate the brush head and bristles during
operation. When the oscillatory device is a power toothbrush, the
detachable accessory may comprise a brush head with bristles and
bristle tufts, or the accessory may comprise a probe or flosser
attachment, or the like. U.S. Patent Publication Nos. 2005/0091770
A1 and 2007/0079455 A1, which are incorporated herein by reference
in their entireties, describe power toothbrushes employing a motor
to oscillate bristles in a brush head and make reference to
numerous publications relating to power toothbrushes. Oscillatory
motors of the present invention are suitable for use in the oral
hygiene devices described in these patent publications. More
generally, numerous accessories or end effectors may be provided
for attachment to a universal handle incorporating an oscillatory
motor of the present invention.
[0012] Detachable accessories that are oscillated by operation of
an oscillatory motor of the present invention may also incorporate
features having active or passive power requirements, such as an
ultrasound transducer, a motorized device or accessory, light
emitting devices, microprocessor controlled circuitry, fluid
devices, and the like. Devices of the present invention preferably
employ a transformer to inductively couple and transfer power from
the power source and/or drive circuitry in one component, such as a
handle, to devices having power requirements, such as transducers,
light emitting devices, circuitry, and the like, provided in a
detachable component or accessory.
[0013] The oscillatory device may additionally incorporate a
rechargeable power source, such as an inductively rechargeable
power source. A charging station connectable to an external power
supply for recharging the batteries may also be provided. The
battery charging station may include active electronics for
charging the batteries from a DC power supply, such as a 12V power
supply, in addition to an A/C power supply.
[0014] Devices of the present invention may additionally
incorporate various user interfaces and control and monitoring
features. A user interface comprising at least an on/off control is
provided and, upon activation of the device by the user, the
oscillatory motor is activated and the oscillatory drive shaft
provides oscillatory drive output. A device controller may provide
a timing function, various operating cycles may be programmed or
programmable, and multiple detachable accessories may be coupled to
a universal handle. Multiple detachable accessories may be
distinguished by a controller and operated according to
predetermined operating cycles. Motor drive oscillatory output may
be varied over an operating cycle or according to predetermined or
selectable programs. In another embodiment, motor drive oscillatory
output may be monitored and varied based on feedback.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] Various aspects and advantages of this invention will become
more readily appreciated and may be better understood by reference
to the following detailed description, taken in conjunction with
the accompanying drawings, wherein:
[0016] FIG. 1 is a schematic, partially cross sectional diagram
depicting an exemplary oral hygiene device of the present
invention;
[0017] FIG. 2A shows an enlarged schematic exploded perspective
view of a limited angle torque motor used in devices of the present
invention;
[0018] FIG. 2B shows a side view of the limited angle torque motor
of FIG. 2A;
[0019] FIG. 2C shows a cross-sectional view of the limited angle
torque motor of FIG. 2B taken through line C-C;
[0020] FIG. 3A shows an enlarged schematic perspective view of a
limited angle torque motor stator assembly comprising a laminated
stack;
[0021] FIG. 3B shows an enlarged schematic perspective view of an
exemplary split coil assembly suitable for use in a limited angle
torque motor stator assembly;
[0022] FIG. 4 shows an enlarged schematic perspective view of
another embodiment of a limited angle torque motor of the present
invention;
[0023] FIG. 5 shows a schematic view of another embodiment of a
limited angle torque motor of the present invention;
[0024] FIG. 6 shows an exploded view of a device handle with a
limited angle torque motor and inductive transformer components
mounted in a device handle;
[0025] FIG. 7 shows an enlarged exploded view of a device accessory
and inductive transformer components mounted in the accessory;
and
[0026] FIG. 8 shows a schematic view of a charging station and
power cord useful in connection with devices of the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
[0027] Oral hygiene devices, such as toothbrushes, are exemplary
oscillatory devices of the present invention, and detailed
embodiments of oscillatory devices are described herein with
reference to power toothbrushes. It will be appreciated that
devices and features of the present invention are not limited,
however, to oral hygiene applications or toothbrushes. The features
described herein may be used in various types of personal hygiene
and other types of personal care and medical devices, as well as
various types of tools. Oscillatory devices of the present
invention may comprise a support structure, such as a handle, for
housing a limited angle torque motor and having at least one
accessory or end effector associated with the support structure
that is oscillated at sonic frequencies. The accessory or the end
effector may include a bristle, a bristle tuft, a prong, a holder
for a detachable implement or material, a razor or skin treatment
implement, an implement for treatment of a body structure or
tissue, or the like.
[0028] FIG. 1 schematically illustrates an exemplary oral hygiene
device of the present invention, a toothbrush, comprising a motor
for generating oscillations at sonic frequencies. Toothbrush 10
comprises a handle 15 constructed from a rigid or semirigid
material, which typically houses at least one rechargeable battery
12 that may be adapted to be induction charged using a charging
device powered by an external power source; a motor 16 for
generating oscillation at sonic frequencies, preferably a limited
angle torque motor incorporating a return mechanism for oscillating
toothbrush head 20 and bristles mounted on the head at sonic
frequencies of less than 1 MHz; and controller 18 that provides
timing, motor control and various other control functions. The
motor may alternatively be mounted in a device accessory that is
integral with or attachable to the handle. Toothbrush 10
additionally comprises an electrical drive circuit 14 for driving
an active or passive electrical or electronic device. In one
embodiment, electrical drive circuit 14 is an ultrasound drive
circuit adapted to drive an ultrasound transducer for producing
acoustic energy at ultrasonic frequencies at the brush head and
motor 16 is mechanically coupled to the brush head by means of an
oscillating drive shaft 17 to produce acoustic energy at sonic
frequencies at the brush head.
[0029] Toothbrush head 20 is mounted on handle 15 and includes a
stem portion 21 and brush head portion 23. Stem portion 21 may
provide a channel or other means for facilitating transmission of
power or instructions to the brush head portion. In the embodiment
illustrated schematically in FIG. 1, brush head portion 23
comprises an ultrasound transducer 22 and a plurality of bristle
tufts 26. The toothbrush head 20 may be either detachably or
fixedly attached to the handle 15 and, in preferred embodiments, is
detachably mountable to handle 15. The brush head portion may then
be provided as a separate, replaceable component. Ultrasound
transducers and modules, acoustic waveguides, and other components
facilitating the use of ultrasound transducers in oral hygiene
devices are described in detail in U.S. Patent Publication Nos.
U.S. 2005/0091770 and U.S. 2007/0079455, which are incorporated
herein by reference in their entireties.
[0030] The device of FIG. 1 illustrates an exemplary oral hygiene
device of the present invention in the form of a power toothbrush.
Additional and preferred embodiments including various ultrasound
and/or sonic operating parameters, device components, control
features, and the like, are described in greater detail in the U.S.
Patent Publications incorporated herein by reference. It will be
appreciated that while certain combinations of operating parameters
and features may be preferred for use in certain applications and
in particular environments, the device components, operating
parameters, control features, and the like, may be combined in many
different ways in oscillatory devices, including oral hygiene
devices, of the present invention.
[0031] Oscillatory drive motors of the present invention are
electrically connected to the power source and may additionally be
connected to a controller. They incorporate a drive shaft for
delivering motor output, e.g. oscillation, to the device or a
device component, or to an accessory such as brush head, to
oscillate the brush head and the bristles at sonic frequencies of
less than 1 MHz. The motor drive shaft typically projects from the
handle assembly and is mechanically coupled to a mating receiving
structure in the accessory or the brush head upon mounting of the
brush head to the handle. For application in handheld and portable
devices, the motor is preferably of a compact and lightweight
design that fits conveniently in a generally cylindrical device
handle.
[0032] Limited angle torque (LAT) devices, which have generally
been used as actuators or feedback devices to provide control of
angular position, velocity and acceleration, are used in
combination with a return mechanism, such as one or more spring(s),
as oscillatory drive motors in devices of the present invention.
The LAT device provides displacement of an output shaft through an
angle of less than 180.degree. and may be configured to provide
limited angular displacement as rotation of the output shaft about
its own longitudinal axis, or to provide limited angular
displacement of the output shaft through an arc, as rotation of the
output shaft about an axis generally perpendicular to the
longitudinal axis of the shaft. The output shaft is returned to its
neutral position following the angular displacement by a centering
mechanism, such as a spring. Various types of springs, such as
torsion springs, clock springs, leaf springs, clothespin springs,
and the like, may be used as return mechanisms in oscillatory drive
motors of the present invention. Oscillatory motors of the present
invention provide a generally constant torque through the angular
displacement and may be designed to provide various ranges of
angular displacements.
[0033] In one embodiment, LAT motors comprise a magnetic rotor
having rare earth permanent magnets that are radially magnetized
and a stator that supports windings in a single phase, so that no
commutation is required for motion to occur. Because the permanent
magnet flux density field is fixed, the direction of rotation
depends on the polarity of input current and the amount of torque
produced is directly proportional to the magnitude of the input
current. In one configuration, described below with reference to
the oscillatory drive motor illustrated in FIGS. 2A-2C, the drive
motor produces rotation of an output drive shaft through a limited
displacement of less than 180.degree. to oscillate the device
accessory and/or end effector(s). In another configuration, an
oscillatory drive motor of the present invention may be used to
produce motion in an arc, or a sweeping side-to-side motion, that
is also suitable for use in various types of oral hygiene and other
oscillatory devices.
[0034] FIGS. 2A, 2B and 2C illustrate an oscillatory drive motor
producing rotational output suitable for use in oscillatory devices
of the present invention. Oscillatory drive motor 100 has a
generally cylindrical exterior configuration and comprises a base
110 from which electrical leads 111, 112 that are connected to a
stator assembly 130 project. Generally cylindrical housing 114 is
mounted to base 110 and encloses rotor assembly 120 and stator
assembly 130.
[0035] Rotor assembly 120 comprises a central and generally annular
core or sleeve 122 on which at least one permanent magnet 124 is
retained. Bearings 125, 126 are mounted on sleeve 122 at opposite
ends of the magnet. Permanent magnet 124 is preferably a radially
magnetized, multipole, rare earth, permanent magnet that is bonded
to the sleeve. Multiple Neodymium Iron Boron or Samarium Cobalt
permanent magnets may be used for the rotor and arranged to provide
an even number of poles (e.g., 2, 4 6, etc.). Drive shaft 140 is
fixedly mounted to the rotor assembly by bonding, for example, to
the rotor sleeve or core. In a preferred embodiment, drive shaft
140 is bonded to rotor sleeve 122 in proximity to an output portion
144 of the drive shaft.
[0036] Stator assembly 130, in this embodiment, is a toroidal coil
assembly comprising toroid core 132 having a coil winding 136
mounted on the toroid core. Toroid core 132 preferably comprises an
electrically insulated, soft magnetic steel toroid. Multiple
sections of coil winding, comprising a magnetic wire material such
as insulated copper magnet wire, are wound around the toroid core
132, forming coil 136. The core 132 may have a generally
cylindrical configuration or may have an elliptical or another
configuration and may comprise a single, unitary core, or split
cores may be provided, forming a toroid coil assembly. The coil
windings may be bonded or encapsulated, and the number of winding
sections of coil 136 corresponds to the number of magnetic poles on
rotor assembly 120. Mounting pins 134 or alternative mounting
mechanisms are provided on coil assembly 130 for fixedly mounting
the coil assembly to the base or to the housing.
[0037] In one embodiment useful for compact, oscillatory motors of
the present invention, the rotor assembly comprises a single
permanent magnet having two opposing poles, and the toroidal coil
comprises two coil segments. The longitudinal dimension of the
rotor magnet 124 is generally similar to the longitudinal dimension
of toroid core 132. Rotor assembly 120 is mounted concentrically
within toroidal coil assembly 130 in the embodiment illustrated.
Non-concentric arrangements of the rotor assembly within the coil
assembly may be used in alternative embodiments and spacers and
other types of mechanical devices may be provided to maintain an
appropriate distance between the rotor and stator assemblies.
[0038] In one embodiment, a motor shaft is mounted, at one portion
(e.g., one end), to a stationary structure, such as the motor base
or another stationary structure in the device, and is mounted at
another portion (e.g. the other end or an intermediate segment) to
the rotor assembly. During operation of the motor, the rotor
rotates and, with it, a drive portion of the drive shaft is rotated
through a limited angular displacement at a desired drive
frequency. The direction of rotation depends on the polarity of the
input current and, for oscillatory motors of the present invention,
the polarity of the input current is generally alternated to
provide angular rotational displacement of the output shaft in
opposite directions sequentially.
[0039] In the oscillatory motor embodiment illustrated in FIGS.
2A-2C, motor shaft 140 is received through the rotor assembly and a
stationary end 142 of motor shaft 140 is fixedly mounted in housing
base 110. Base 110 may be provided with a keyed bore 115 for
receiving a mating, keyed portion of stationary end 142 of motor
shaft 140. An opposite end of motor shaft 140 is bonded to the
sleeve 122 of the rotor assembly 120. A drive section 144 of the
drive shaft extends from motor housing 114 for driving or
oscillating a load. A drive portion of drive section 144 may be
provided with a flat 145, or another mechanism for mating with a
complementary structure in an accessory component, such as a
toothbrush head, and orienting the device head with respect to the
shaft in both radial and axial orientations.
[0040] Oscillatory motors of the present invention preferably
incorporate or operate in conjunction with a centering or return
mechanism, such as a spring, that re-aligns or returns the poles of
the permanent magnet in the rotor assembly to the midpoint of the
coil segments of the stator assembly following rotation of the
rotor and limited angular displacement of the drive shaft. In one
embodiment, the centering mechanism may comprise a torsion spring
that returns the shaft to its neutral position following the
limited angular displacement. The centering mechanism, in addition
to providing the alignment function, allows the rotor assembly to
be used as an oscillating resonant system.
[0041] In one embodiment, the centering mechanism is provided as a
torsion spring forming an integral part of drive shaft 140. As
illustrated in FIG. 2A, necked down segment 146 of drive shaft 140
in the area of rotor assembly 120 provides a smaller diameter shaft
portion that acts as a centering torsion spring mechanism for the
oscillatory motor. In this embodiment, the drive shaft comprises at
least one larger configuration segment and at least one smaller
configuration segment, with the smaller diameter segment positioned
in proximity to the rotor assembly. The drive shaft, as illustrated
in FIGS. 2A and 2C, may have two larger diameter segments of
unequal dimensions positioned on either side of and formed
integrally with the smaller diameter necked down segment 146. The
geometry and tensile properties of the smaller diameter segment of
the drive shaft forming the torsion spring may be adjusted
depending on the angular displacement of the motor, the oscillatory
output required, the weight distribution of the driven mass, and
the like.
[0042] The smaller configuration drive shaft segment that serves as
a torsion spring in the embodiment illustrated in FIGS. 2A-2C may
have a length of from about 50% to about 200% the length of the
rotor magnet, preferably from about 75% to about 150% the length of
the rotor magnet. The cross-sectional configuration of drive shaft
torsion spring may be cylindrical or may have a flattened profile
and may be constant along its length or variable. In one
embodiment, for example, the cross-sectional configuration of the
drive shaft torsion spring may be tapered. In one embodiment, the
cross-sectional configuration of torsion spring 146 generally
matches the cross-sectional configuration of the drive section 144
and has a diameter of from about 20% to about 80% the diameter of
drive section 144. The torsion spring segment of the drive shaft
may be constructed from a material that is the same as that of the
rest of the drive shaft, or it may be different and have different
tensile properties. In alternative embodiments, the torsion spring
may be provided as a flat, pancake-like structure.
[0043] The centering mechanism may be integrally formed with the
motor shaft within the oscillatory motor housing, as shown in the
embodiments illustrated in FIGS. 2A-2C, or it may be provided on an
extension of the motor shaft outside the rotor assembly and/or the
motor housing. Incorporating the centering mechanism within in the
body of the rotor assembly facilitates design of a compact
oscillatory motor assembly having a generally low motor housing
length to diameter ratio. In some embodiments, the motor housing
length (L) to diameter (D) ratio is less than about 1:2 and may be
less than about 1:1.5. In some embodiments, the oscillatory motor
housing length L is less than less than about 1.5 inch and, in some
embodiments, is less than 1 inch.
[0044] The geometry and tensile properties of the torsion spring
segment of an oscillatory drive shaft, as well as the geometry and
properties of the drive segment of the drive shaft, may be adjusted
depending on the angular displacement of the motor, the oscillatory
output required, the mass of the load being oscillated, and the
like. In general, oscillatory motors of the present invention are
capable of driving a relatively high mass and inertia accessory,
such as a toothbrush head, having a mass and inertia on the order
of about 10.sup.-8 Kg/m.sup.2 at sonic frequencies of less than
about 1 MHz.
[0045] FIGS. 3A and 3B illustrate alternative stator components and
assemblies for use in oscillatory LAT motors of the present
invention. The stator assembly illustrated in FIGS. 2A-2C comprises
a toroidal coil assembly having a generally solid toroidal core.
FIG. 3A shows a stator assembly 130' comprising a toroidal coil
assembly having a laminated stack 131 forming the toroidal core.
The stator assembly 130' is otherwise similar to that described
above with reference to stator assembly 130. The toroidal core may
be provided as a unitary, single piece core or, as shown in FIG.
3B, it may comprise two or more separate components assembled to
provide a core. FIG. 3B shows a split laminated core section 130''
integrating structures for mounting to a mating core section to
provide a stator assembly. Split core section 130'' comprises
eyelets 133A, 133B and a pin receiving structure 135 for mating
with complementary structures on another split core section.
Insertion of mounting pins through the complementary mating
structures provides a unified core for a toroidal coil assembly of
the present invention. Two split cores as illustrated in FIG. 3B
may be assembled to form a core for a toroidal coil assembly; it
will be appreciated that split cores may be provided in various and
multiple arced segments.
[0046] In operation, when the stationary coil stator assembly is
electrically energized, a magnetic field is produced, which causes
the permanent magnet in the rotor assembly to rotate with respect
to the coil. This rotation of the rotor is mechanically transferred
to the segment of the drive shaft mounted to the rotor assembly.
Rotation of the rotor assembly thus rotates a portion of the drive
shaft in a first direction A, as shown in FIG. 2C, while another
portion of the drive shaft is fixedly mounted to a stationary
structure, producing the torque output of the motor. In the
oscillatory motor assembly of the present invention, as one segment
of the drive shaft is rotated with the rotor assembly and another
segment of the drive shaft remains in a fixed position with respect
to the motor housing, the smaller diameter torsion spring segment
146 of the drive shaft is twisted, or torqued. When the coil is
de-energized, the rotor returns to its centered, generally
concentric position and the torsion spring returns to its untwisted
state. The toroidal coil may then be energized in the opposite
direction, shown as direction B in FIG. 2C, rotating the rotor and
the drive segment of the drive shaft, and the torsion spring is
twisted in the opposite direction. Again, when the coil is
de-energized, the torsion spring returns to its untwisted state and
the rotor returns to its centered, concentric position.
[0047] This alternating pattern of rotor and drive shaft rotation,
and the consequent twisting of the torsion spring in opposite
directions, repeatedly rotates a drive segment of the drive shaft
along a limited angular rotational path in opposite directions. For
many devices and applications described herein, the rotational
output of drive portion 144 of drive shaft 140 is less than
20.degree. peak to peak, or less than 10.degree. in both directions
from a neutral position. In some embodiments, the angular output of
drive portion 144 of drive shaft 140 is less than 10.degree. peak
to peak, or 5.degree. in both directions from a neutral position.
In yet other embodiments, the angular output of drive portion 144
of drive shaft 140 is between about 2.degree. and 8.degree. peak to
peak, or between about 1.degree. and 4.degree. in both directions
from a neutral position. For oscillatory oral hygiene devices
operating at the frequencies described herein, the angular output
of the drive portion 144 of motor shaft 140 is generally from about
2.5.degree. to about 6.degree. peak to peak, and for some
applications is between about 3.degree. and 5.degree. peak to
peak.
[0048] Oscillatory motors having a stationary, arced, multiple pole
permanent magnet stator assembly and a wound wire rotor may also be
used in oscillatory devices of the present invention to provide
displacement of an output shaft through an arc rather than as
rotation about a shaft. FIG. 4 illustrates an exemplary arc output
LAT motor of the present invention. Oscillatory drive motor 300
comprises an arced magnetic stator assembly 330 and a rotor
assembly 320. In this embodiment, the rotor assembly has a coil
comprising, for example, copper magnet wire, mounted to a portion
of an output shaft 340. Another portion of the output shaft, fixed
end 342, is mounted to a stationary structure.
[0049] When the stator assembly is energized, and the coil rotor
moves angularly in one direction along the arc of the magnetic
stator and, with it, an output portion 344 of output shaft 340 is
displaced through a similar arc. The rotor and output portion of
the output shaft are displaced in opposite directions when the
polarity of the input current is changed. Oscillatory drive motor
300 preferably comprises a centering mechanism to return the output
drive shaft portion 344 to a neutral position. In the embodiment
illustrated in FIG. 4, a spring, such as a leaf spring 346, is
formed integrally with output shaft 340.
[0050] In an alternative embodiment, the stationary stator assembly
may comprise multipole permanent magnets mounted on plates that are
spaced to provide gaps, as shown in the embodiment schematically
illustrated in FIG. 5. In this embodiment, rotor assembly 150
having output shaft 152 is mounted in a gap formed between
multipole permanent magnets 153, 154 are mounted on spaced apart
plates 155, 156. The stationary multipole permanent magnets carried
by the plates form the stator and, during operation, displace the
rotor assembly, and the output shaft, through an arc. The rotor and
output portion of the output shaft are displaced in opposite
directions when the polarity of the input current is changed, and a
centering mechanism is provided to return the output drive shaft to
a neutral position.
[0051] The combination of the limited angle torque motor of the
present invention incorporating a centering mechanism, and its
association with the rotor assembly and the driven mass, such as
the accessory device head mechanically coupled to the drive portion
of the motor shaft during operation, forms a resonant system. The
spring/rotor/driven mass system has a resonant oscillatory
frequency that is a function of the moment of inertia of the
rotating mass and the spring rate. In preferred devices of the
present invention, the moment of inertia of the mass and the spring
rate are coordinated so that the resonant frequency of this
resonant system is substantially similar to the desired operating
frequency of the device accessory (e.g. toothbrush head) and/or end
effector(s). Coordinating the resonant frequency of the drive
system and the desired device operating frequency is desirable for
many applications because it reduces the power consumption of the
motor. Alternative embodiments in which the resonant frequency of
the spring/rotor/driven mass system and the desired device
operating frequency are not matched are also useful for many
applications.
[0052] The acoustic waveform of sonic oscillations, as generated in
devices of the present invention, is generally sinusoidal, but
other waveforms may be used--additionally or alternatively. Sonic
oscillations may be driven in non-sinusoidal waveforms, for example
trapezoidal, triangular, square, purely rotational, and other
waveforms. Additionally, the frequency and/or amplitude may be
modulated. The frequency of sonic oscillation influences the
effectiveness of the device and may additionally influence user
comfort and the user's perception of device effectiveness.
[0053] For many applications and oscillatory devices of the present
invention, the preferred resonant frequency of the
spring/rotor/device head system and the preferred oscillating
frequency of the driven mass is between about 20 Hz and 10,000 Hz.
In a device incorporating one or more end effectors such as bristle
tufts or bristles, oscillation of the brush head or accessory at
sonic frequencies produces bristle tip motion. Bristle tip motion
may be characterized by bristle tip velocity, amplitude, frequency,
acceleration, and other metrics. Devices of the present invention
employing an oscillatory motor preferably operate to produce
bristle tip frequencies of greater than 20 Hz and less than 20,000
Hz. High bristle tip frequencies are irritating to many users and
may create an undesirable tickling sensation in the oral cavity.
For this reason, bristle tip frequencies of less than about 2,000
Hz are preferred for many oral hygiene device applications. A
desired sonic operating frequency may be a note on the musical
scale, most typically those have a frequency greater than about 54
Hz and less than about 1662 Hz. According to some embodiments,
operation of the oscillatory motor produces bristle tip frequencies
of less than about 1500 Hz. Bristle tip frequencies of less than
about 1000 Hz are preferred for many applications; bristle tip
frequencies of less than about 500 Hz are preferred for yet other
embodiments. In still other embodiments, bristle tip frequencies of
greater than about 50 Hz and less than about 500 Hz are preferred;
in yet other embodiments, the oscillatory motor is operated to
produce bristle tip frequencies of between 100 and 300 Hz.
[0054] To maintain a generally constant bristle tip velocity as the
frequency increases, the bristle tip amplitude decreases.
Similarly, to maintain a substantially constant bristle tip
velocity as the amplitude increases, the frequency decreases. Both
frequency and amplitude of bristle tip movement may affect cleaning
and user comfort. Oral hygiene devices of the present invention
employing a limited angle torque oscillatory motor, intended for
use in the environment of a dentifrice slurry and employing
sinusoidal sonic motion, generally operate to produce a desired
peak bristle tip velocity during an operating cycle, of from 0 to
10 m/s, more typically from 0.2 to 5 m/s, more typically from 0.4
to 3.0 m/s and generally greater than 1.0 msec and less than 3.0
m/s. For some embodiments, the bristle tip velocity during
operation is less than about 1.5 m/s, often less than 1.0 m/s, and
in some embodiments between about 0.4 and 0.8 m/s. Bristle tip
velocity measurements are taken with the bristles dry, in air,
without an applied load to the bristle tips. Actual bristle tip
velocity is generally reduced during operation as a result of
loading associated with frictional contact of the bristles against
teeth and drag associated with moving bristles through a fluid
environment.
[0055] The peak amplitude of bristle tip motion during an operating
cycle or subcycle may range from about 0.01 to 10 mm. A preferred
range of peak bristle tip amplitude (as wetted and typically loaded
in the oral cavity) is in the range of 0.1 to 6 mm, and is
generally less than 4.0 mm. According to further embodiments, the
peak bristle tip amplitude is less than 3.0 mm and may be in the
range of from 0.2 to 3.0 mm or from 0.4 to 2.2 mm. Bristle tip
amplitude measurements are taken with the bristles dry, in air,
without an applied load to the bristle tips.
[0056] An exemplary device handle housing an oscillatory motor of
the present invention and other components typically mounted in the
handle housing is illustrated in FIG. 5. Handle 200 is generally
rigid and has a generally cylindrical profile, with an internal
cavity and associated internal mechanical structures for retaining
the components shown. The housing may comprise an integral, hollow
cylindrical component or it may be formed in one or more pieces,
such as an upper and lower part, that are joined during handle
assembly. Handle 200 may also incorporate one or more user
interface(s), such as on/off button 202, battery charge level
indicator 204 and brush head replacement indicator 206.
[0057] The motor and other components mounted in the handle that
require power may be powered by direct connection to an electrical
power source, such as through a conventional cord and plug.
Alternatively, the handle may incorporate a battery source for
power and may, in preferred embodiments, incorporate a rechargeable
battery source. In devices incorporating an inductively
rechargeable battery source, a charge coil 210 and charge core 212
are generally provided in the base of the handle assembly for
inductive charging from a separate charging station accessing a
power supply (See FIG. 8). Charge coil 210 is electrically
connected to one or more rechargeable batteries 214 that supply the
power requirements for the device. Suitable rechargeable batteries
include, for example, Nickel Cadmium (NiCad) batteries and NiMH
(Nickel metal hydride) batteries. In the embodiment shown in FIG.
6, batteries 214 are mounted in a mechanical carrier structure 216
that provides mechanical support for the batteries and also
supports a controller or circuit board assembly 218. The batteries
are preferably located near the center axis of the handle assembly
to provide a desirable weight balance to the handle. This housing
design allows the shape to be large in the center and taper down at
the top and bottom. Different designs of the lower section may be
used for different versions of the handle assembly.
[0058] In the embodiment illustrated in FIG. 6, a single circuit
board assembly 218 is provided and all control and monitoring
functions, as well as accessory feature drive circuitry, is
provided on the single circuit board. It will be appreciated that
these functionalities may be provided on separate circuit boards
located in separate locations within the handle, and that
additional circuit boards providing additional functionality may
also be provided.
[0059] Oscillatory devices of the present invention may have a
unitary construction or may comprise multiple, detachable
components that employ conventional electrical or magnetic contacts
to transfer power to components having active or passive power
requirements, such as an ultrasound transducer, illumination
feature(s), circuitry, and the like, that operate in an accessory
component. In one embodiment of an oscillatory device of the
present invention, the oscillatory motor is housed in a device
handle and one or more components having active or passive power
requirements are housed in a detachable accessory component. In
this embodiment, inductive coupling of the handle to the accessory
component may be provided by a transformer assembly to transfer
power from the power source and drive circuitry in the handle to
the component(s) in the accessory device head. The transformer
assembly may additionally provide a step-up of voltage from power
supply circuitry to the powered component and additionally provide
a physical separation of the transformer primary and secondary side
components when the head assembly is detached from the handle. The
transformer assembly also provides electrical isolation between the
power supply circuit(s) in the handle and the accessory component
circuit in the accessory assembly.
[0060] Suitable transformers typically employ a primary and
secondary split between the handle and accessory assembly. In one
embodiment, a power supply circuit and primary side coil and core
of the transformer are mounted in the device handle, and electrical
contacts extend from the transformer primary coil into the main
handle compartment for connection to a power supply. As illustrated
in FIG. 6, the transformer primary coil 228 (electrical contacts
not shown) and core 226 components are generally provided in the
device handle isolated from the other components mounted in the
handle by means of spacer 224 and sealed plug 230. The secondary
side coil 232 (electrical contacts not shown) and core 234 of the
transformer assembly are mounted in the device head assembly 240
and sealed by cover 236, as illustrated in FIG. 7. The transformer
assembly, in this embodiment, delivers an impedance-matched voltage
required by the active electrical component provided in the
accessory to produce the desired component output. The secondary
coil and core, mounted in the accessory, may be mounted in an
enlarged housing section 242.
[0061] The transformer coil assemblies are typically wound on a
bobbin in a circular or elliptical path and sealed. Annular cores
having an aperture in the center that permits the oscillatory motor
drive shaft to pass through the transformer assembly and
mechanically couple to the accessory or another driven mass are
preferred for many applications. A small air gap (typically from
about 0.010 to 0.150 inch, more typically less than 0.010 inch and,
in some embodiments, between 0.040 and 0.080 inch) between the
transformer core mounted in the handle and the transformer core
mounted in the accessory is desirably maintained during operating
cycles for efficient operation of the transformer and inductive
power transfer. Within certain embodiments, the air gap between the
cores may be achieved by using sealed coil assemblies and having
the cores mounted outside these sealed assemblies. In an
alternative embodiment, a ferroelectric fluid or ferro-filled
elastomer may be used as a filler composition between the cores to
improve transformer efficiency.
[0062] Alternative transformer designs are also contemplated. These
include, without limitation, the use of toroid wound core or
lamination stacks to form the core. Regardless of the precise
transformer assembly adopted, it may be desirable to have the
primary and secondary portions of the transformer split between the
handle and toothbrush head assembly.
[0063] Within certain embodiments of the present invention, the
transformer assembly used for power coupling between the device
head assembly and the handle may provide power to other devices
requiring power in the device head, and may further provide for the
exchange of electrical information between the device head and the
handle. This may, for example, be achieved by adding a coil, or an
additional coil winding(s), to the primary side of the transformer
assembly, or by using a center taped coil, that inductively couples
signals to the coil (or coils) in the device head (i.e. the
secondary side of the transformer). Thus, a signal may be sent from
the handle to the toothbrush head assembly and a corresponding
response provided by the toothbrush head assembly components.
Alternatively, signals between the primary and secondary sides of
the transformer may be coupled to induce a voltage on top of the
ultrasonic drive waveform. This may, for example, provide an
amplitude modulation signal riding on top of the ultrasound
waveform. Alternatively, the signal frequency may be modulated to
provide frequency modulation or a combination of frequency
modulation and amplitude modulation.
[0064] This additional transformer component may, optionally, be
employed to provide a feedback signal for monitoring performance of
an active electrical component, such as an ultrasound transducer,
mounted in the accessory. Such feedback may, for example, control a
voltage controlled oscillator (VCO) and/or a phase locked loop
(PLL) for self-tuning the oscillator frequency to the transducer,
to monitor operation of the ultrasound transducer at the initiation
of, or during, an operating cycle or subcycle.
[0065] Oscillatory devices of the present invention comprising
transformers with one or more extra coil(s), or additional coil
winding(s), may incorporate additional device functionality. In one
embodiment, for example, the additional coil, or coil winding(s),
is primarily used for interaction with an ultrasound transducer
power supply circuit. In another embodiment, an additional coil, or
coil winding(s), is employed to monitor the performance of an
ultrasound transducer. In another embodiment, an additional coil,
or coil winding(s), actuates an ultrasound transducer assembly and
monitors the performance of the transducer. In yet another
embodiment, an additional coil, or coil winding(s), is used for
testing and/or calibration of components mounted in the handle
and/or device head assembly. In still another embodiment, an
additional coil and/or coil winding(s) is used to sense the
environment in which the device is used, such as properties in a
user's mouth and/or on a user's teeth, and communicate that
information to a controller. In another embodiment, an additional
coil and/or winding(s) is used to determine and/or signal the
acceptable or unacceptable performance of an ultrasound transducer
or another active electrical component and/or the end of the useful
life of an accessory or device head. In yet another embodiment, an
extra coil and/or winding(s) may be used to monitor an active
component for a unique signature, thereby identifying an accessory
and initiating operating cycles based on the sensed accessory.
[0066] Accessories oscillated by an oscillatory motor housed in a
handle and, optionally, having active components powered
inductively by means of a transformer assembly, are preferably
detachable from the handle assembly and replaceable. Features of
the accessory are illustrated by reference to the toothbrush head
assembly illustrated in FIG. 7. Accessory toothbrush head assembly
240 comprises a substantially rigid housing structure, having a
base portion 242 for attachment to a mating attachment region on
the handle, a smaller cross-section stem portion 244 and a brush
head support structure 248. The accessory brush head may
incorporate an ultrasound transducer module, and/or one or more
bristle tufts 250, as well as the previously described components
for transmitting power to the active component and for coupling
oscillatory motion to the accessory and bristle tufts. In
embodiments that don't incorporate a transformer assembly,
electrical power may be provided to the accessory active component
by hardwired electrical connections established by positive contact
of complementary electrical contacts mounted in the handle and the
accessory upon attachment of the accessory to the handle.
[0067] Electrical connection between the secondary coil 232 mounted
in the toothbrush head assembly and the active component (e.g.,
ultrasound transducer assembly) may be accomplished by means of
(one or more) conductive electrodes that contact the transducer
assembly contact(s) and contacts provided at the secondary coil.
One or more conductive electrode(s) may be provided as conductive
metal strips retained in channel(s) in the brush head assembly and
may be molded into the brush head structure. Alternatively,
flexible electrical connections (e.g., jumper-type connections) may
be used between the transducer assembly contacts and the coil
contacts. In an alternative embodiment, the electrical contacts
attach mechanically to the non-moving part of the brush head
housing so that the contact provides a spring force to return the
brush head to a center position or another desired position.
[0068] The bristle tufts 250 are mounted on a support plate or on
the support structure 248. Accessory device heads of the present
invention, and particularly toothbrush heads, typically incorporate
assemblages of one or more bristle tufts, each tuft comprising a
bundle of one or more bristle filaments. Many types of bristle
filaments are available and may be used in device heads of the
present invention. In general, bristle filaments, and tufts, may be
characterized by the material of the filaments, the diameter,
cross-sectional configuration and exposed length of each filament
and tuft, the stiffness or flexibility of filaments and tufts, and
the like. The filaments within each tuft may comprise the same
material and have the same dimensional properties, or more than one
bristle type, shape or size may be incorporated in a single bristle
tuft. Likewise, multiple bristle tufts forming the assemblage may
comprise the same dimensional and/or physical properties, or
bristle tufts having different dimensional properties, lengths,
stiffnesses, and the like, may be provided in various arrangements
on the brush head. The tufts may comprise bristle filaments of a
particular shape and/or size to facilitate both cleaning and user
experience. Bristles of a particular shape may be positioned and
oriented to complement the presence of a waveguide in the brush
head. For example, stiffer bristles and bristle tufts (having a
generally greater filament cross section and/or shorter bristle
length) may be positioned to facilitate orientation of the
waveguide at a particular position with respect to the teeth, and
softer bristles (having a generally smaller filament cross-section
and/or longer bristle length) may be positioned to facilitate
waveguide penetration at interproximal spaces.
[0069] Devices of the present invention generally incorporate Power
On and Power Off control mechanism(s) that are operable by the
user. In one embodiment, a mechanical actuator is provided that,
upon application of pressure, activates the device to initiate an
operating cycle. Initiation of the operating cycle generally
involves activation of the motor drive and/or ultrasound transducer
and may incorporate a delay feature that delays initiation of the
operating cycle for a predetermined period. The same mechanical
actuator may be used to inactivate the device and terminate an
operating cycle, or the device may be programmed to automatically
shut off after termination of an operating cycle or following a
predetermined delay period after termination of an operating cycle.
An indication that the device has been activated may be provided by
illuminating a Power On button, for example, using LEDs. In
addition to Power On and/or Power Off controls, devices of the
present invention may have one or more predetermined programmed
operating cycles that are selectable by a user. Alternatively,
devices of the present invention may be programmable by the user to
provide one or more operating cycles selectable by one or more
users. Devices of the present invention may additionally
incorporate detection features, for example, that allow initiation
of an operating cycle only when a device head is appropriately
coupled to a device handle, or only when a device head is
determined to be operational. In the event a non-functional device
head is mounted or a device head is mounted improperly, a user
interface may signal the user to make an appropriate
correction.
[0070] Additional user interfaces may be provided. The level of the
battery charge may be enunciated to a user, for example, by
illuminating a display visible to the user using LEDs. Variations
in the level of charge may be communicated and visualized, for
example, by illuminating different quantities or patterns of
signals. A user interface may also be provided to indicate that the
device head is functioning properly, or that the device head is not
functioning. Any type of user interface may be implemented
including illumination of an indicator using one or more LED
display(s), one or more LCD display(s), an audible tone(s), a pause
or change in the operation of the drive motor, or the like. Such
indicators may be incorporated variously and in different positions
on the device, such as on the handle, on an accessory charging
device, on a device head, or on an accessory control device.
[0071] A device head, and a device handle, may incorporate an
identifier that distinguishes a head or handle from others. Such an
identifier may take the form of a color or pattern coded band,
light, or other identifying indicia, or may be provided as an
electronic identifier detectable upon mounting of the device head
in the handle, or by means of an accessory device. Multiple device
heads and/or multiple types of device heads may be used with a
common handle and may be distinguishable by the user and/or by the
controller upon mounting of the device head on the handle. In one
embodiment, a device head identifier may be associated with one or
more operating protocols such that upon initiation of an operating
cycle, the device identifies the device head and runs an operating
protocol associated with that device head. Alternatively, if any
device head is associated with more than one operating protocol,
the device may prompt a user to select a protocol upon or prior to
initiation of an operating cycle. The device may similarly detect
different types of device heads and initiate appropriate operating
cycles depending on the detection and identification of the
operating head.
[0072] The device controller may provide a timing function that
separates a device operating cycle into a plurality of operating
subcycles. A plurality of pre-programmed operating periods may be
provided, for example, with an audible tone and/or a momentary
pause or change in operating conditions producing a
user-perceptible division of subcycles. In one embodiment, for
example, four generally equal operating subcycles may be provided
in a toothbrush of the present invention, providing convenient
operation in the four brushing quadrants in the oral cavity. In
another embodiment, four generally equal operating subcycles may be
provided, followed by a fifth subcycle that is equal or unequal in
time to the four previous subcycles. The duration of the operating
cycle, for toothbrush applications, may be from about 1 min to 3
min, with operating subcycles generally having a duration of from
about 10 sec-45 sec. It will be recognized that any number and
combination of subcycles, periods and/or routines may be provided
and may be preprogrammed in the device or may be programmable by
the user. If multiple preprogrammed subcycle routines are provided,
a user interface is provided to allow user selection.
[0073] For some oral hygiene applications, the oscillatory motion
(bristle tip velocity, amplitude and/or frequency) is desirably
greater during some periods of an operating cycle and/or an
operating subcycle than at others. In some embodiments, therefore,
the motor drive output producing oscillatory motion is variable
over an operating cycle of the device. In another embodiment,
devices of the present invention employing a drive motor are
capable of determining and controlling the desired motor drive
operating frequency by monitoring the resonant operating conditions
of the motor. The controller may, for example, monitor both the
current drawn by the drive motor and the drive frequency of the
motor on a continuous or intermittent basis. The resonant frequency
of the motor is detectable by monitoring the current, since the
current required is lower when the motor operates at its resonant
frequency. The controller may then set the drive motor operating
frequency to a desired offset from the determined resonant
frequency, or vary the drive motor operating frequency to achieve a
desired resonant frequency under different operating
conditions.
[0074] Alternatively, the motor operation may be monitored on a
continuous or intermittent basis and the electromotive force (EMF)
detected from the motor may be used to determine the natural
resonant frequency of the motor and/or its driven system, including
the brush head. Since the resonant frequency is different with and
without the brush head installed, this system may be used to
determine if a brush head is attached to the handle. Multiple brush
heads having different inertia properties may also be detected and
identified using this system, thereby identifying different users
and, optionally, matching different protocols or programmed
features to the different users and/or brush heads. This system may
also be used in conjunction with a brush head replacement feature,
to detect and identify replacement brush heads and thereby trigger
a reset operation.
[0075] An accessory device may also be used, in conjunction with
the controller monitoring the drive motor frequency, to monitor the
angular amplitude for each frequency. The resonant frequency of the
motor is detectable by monitoring the angular amplitude for each
frequency. The angular amplitude measurements may be communicated
to the controller, which then sets the drive motor operating
frequency based on the determined resonant frequency, as above.
[0076] The oscillatory device of the present invention may
incorporate batteries that are rechargeable using an inductive
charging assembly as illustrated in FIG. 8. FIG. 8 illustrates a
charger assembly including an inductive charger base 260
incorporates recess 262 and an open access area that facilitates
placement of a mating device handle in the charger base.
[0077] Base 260 is preferably constructed from a rigid,
non-conductive material, such as a rigid plastic, and may be
provided with one or more non-skid stabilizers on its bottom
surface. Base 260 has an internal space enclosing an inductive
coupling coil and core for inductive charging of the batteries
through the complementary charge coil/core combination in the
handle.
[0078] Base 260 is electrically connectible to an electrical source
through plug 270 by means of flexible cord 280. Plug 270 may have
prongs and be configured to connect to an alternating current
source, such as a standard electrical outlet, or may be configured
to connect to a direct current source. Cord 280 has a plug 282 that
mates with receptacle 266 in charger base 260 and is electrically
connected to plug 270 at its opposite end. A single prong or
multiple prong plug/receptacle combination may be provided. In one
embodiment, cord 270 is detachably connectible to charger base 260
by means of the detachable connection of plug 282 to receptacle 266
to permit more convenient storage and charging of the device. In
one embodiment, charger base 260 comprises active charging elements
that permit inductive charging of rechargeable batteries in the
handle from multiple electrical sources, such as from an
alternating current (AC) source, or from a direct current (DC)
source.
[0079] All references to ranges of parameters described in this
specification are understood to include reference to a range equal
to and greater than the lower value of each range, as well as
ranges equal to and less than the higher value of each range. Thus,
for example, the recitation of a carrier frequency of between about
250 and about 500 kHz in this specification is interpreted to
include carrier frequencies of 250 kHz and greater; carrier
frequencies of 500 kHz and less; as well as carrier frequencies
within the stated range.
[0080] It will be appreciated that while the use of an oscillatory
limited angle torque motor to oscillate a device or a device
accessory or end effector at sonic frequencies has been described
with reference to a power toothbrush, this arrangement may be used
in other types of oral hygiene devices and, indeed, in other types
of personal care and medical devices, as well as tools. The
combination of the oscillatory motor of the present invention with
a transformer assembly for providing power to active components in
a detachable accessory likewise has application for many types of
oscillatory devices.
* * * * *