U.S. patent number 3,828,770 [Application Number 05/318,428] was granted by the patent office on 1974-08-13 for ultrasonic method for cleaning teeth.
This patent grant is currently assigned to Ultrasonic Systems, Inc.. Invention is credited to Lewis Balamuth, Manuel Karatjas, Arthur Kuris.
United States Patent |
3,828,770 |
Kuris , et al. |
August 13, 1974 |
ULTRASONIC METHOD FOR CLEANING TEETH
Abstract
A method for cleaning teeth by providing bursts of ultrasonic
mechanical vibration at an applicator repeated at a sonic frequency
to produce both ultrasonic and sonic vibratory motion and effect
during use of said applicator.
Inventors: |
Kuris; Arthur (Riverdale,
NY), Balamuth; Lewis (Southampton, NY), Karatjas;
Manuel (Glen Oaks, NY) |
Assignee: |
Ultrasonic Systems, Inc.
(Farmingdale, NY)
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Family
ID: |
26817203 |
Appl.
No.: |
05/318,428 |
Filed: |
December 26, 1972 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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119298 |
Feb 26, 1971 |
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209971 |
Dec 20, 1971 |
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Current U.S.
Class: |
601/142; 15/22.1;
433/216; 318/116 |
Current CPC
Class: |
B26B
21/38 (20130101); A61C 1/07 (20130101); B23Q
1/0036 (20130101); A61C 17/20 (20130101) |
Current International
Class: |
B23Q
1/00 (20060101); A61C 17/16 (20060101); A61C
17/20 (20060101); B26B 21/38 (20060101); A61C
1/00 (20060101); A61C 1/07 (20060101); B26B
21/08 (20060101); A61h 007/00 () |
Field of
Search: |
;128/24A,62A
;32/65,66,50 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Trapp; Lawrence W.
Parent Case Text
CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a continuation-in-part of our co-pending patent
applications, assigned to the assignee of the present invention,
Ser. No. 119,298 filed Feb. 26, 1971, entitled ULTRASONIC KITS AND
MOTOR SYSTEMS, and a continuation-in-part thereof, Ser. No.
209,971, filed Dec. 20, 1971, entitled ULTRASONIC DENTAL AND OTHER
INSTRUMENT MEANS AND METHODS, which entire subject matter of the
co-pending applications are incorporated herein by reference as if
fully set forth herein.
Claims
What is claimed is:
1. The method of performing work on an object, comprising the steps
of:
A. positioning an applicator capable of physical vibration at an
ultrasonic frequency adjacent the object;
B. inducing vibrations in said applicator at a frequency in the
ultrasonic range of 10 KHz to 1,000 KHz; and
C. modulating the ultrasonic frequency of said applicator at a
sonic frequency in the range of 10 Hz to 1,000 Hz to produce bursts
of ultrasonic vibrations in said applicator repeated at said sonic
frequency.
2. The method as defined in claim 1, wherein said applicator is
longitudinally vibrated.
3. The method as defined in claim 1, wherein said ultrasonic
frequency is in the range of 20 KHz to 60 KHz.
4. The method as defined in claim 1, wherein said sonic frequency
is in the range of 10 Hz to 1,000 Hz.
5. The method as claimed in claim 1, wherein said applicator is in
the form of a toothbrush.
6. The method as defined in claim 1, and further including the step
of engaging said applicator against the object.
7. The method of simultaneously applying a micro-motion and a
macro-motion to a surface, comprising the steps of:
A. generating ultrasonic vibrations in the working end of a
hand-held ultrasonic motor to produce peak accelerations in said
working end of the order of at least 1,000g;
B. modulating the amplitude of ultrasonic vibrations at a sonic
rate in the range of 10 Hz to 1,000 Hz so as to produce bursts of
ultrasonic vibration repeated at a sonic rate; and
C. simultaneously applying said working end against said surface in
a relative moving relationship with respect thereto, whereby said
micro-motion and macro-motion are transmitted thereto.
8. The method as defined in claim 7, wherein the width of each of
said bursts of ultrasonic vibration and the interval therebetween
are essentially equal.
9. The method as defined in claim 7, wherein said working end is in
the form of a toothbrush.
10. The method as defined in claim 7, wherein said working end is
longitudinally vibrated.
11. The method of removing foreign matter, including plaque and
other surface deposits from teeth comprising the steps of:
A. positioning adjacent the teeth to be cleaned a surface capable
of supporting and transmitting ultrasonic vibrations without damage
to said teeth;
B. vibrating said surface at an ultrasonic frequency in the range
of 10 KHz and 500 KHz;
C. modulating said ultrasonic frequency vibrations of said surface
at a sonic frequency in the range of 10 Hz to 1,000 Hz to produce
bursts of ultrasonic vibration repeated at a sonic frequency rate;
and
D. moving said vibrating surface relative to said teeth such that
it engages and removes the foreign deposits therefrom.
12. The method as defined in claim 11, wherein said surface is
composed of a plastic material.
13. The method as defined in claim 11, wherein said ultrasonic
frequency is in the range of 20 KHz to 60 KHz.
14. The method as defined in claim 11, including the step of
providing a fluid film between said surface and said teeth, said
ultrasonic vibrations being of an amplitude to produce a
cavitational action in said fluid film when said surface is
displaced from said teeth.
15. The method as defined in claim 14, wherein said surface is in
the form of a plurality of individual bristle elements such that
the elements assume positions in which they are randomly divided
between actual contact with and displacement from the surfaces of
said teeth.
16. The method of removing foreign matter, including plaque and
other surface deposits from teeth by simultaneously applying a
micro-motion and macro-motion to the teeth surfaces, comprising the
steps of:
A. generating ultrasonic vibrations in bristle elements at the
working end of a hand-held ultrasonic motor;
B. amplitude modulating said ultrasonic vibrations at a sonic rate
so as to produce bursts of ultrasonic vibrations repeated at a
sonic rate; and
C. engaging said bristle elements against said teeth surfaces at a
relative moving relationship.
17. The method as defined in claim 16, wherein each of said bursts
of ultrasonic vibrations is of a width equal to the interval
between said bursts of ultrasonic vibration.
18. The method as defined in claim 16, including the further step
of providing a fluid film at the teeth surfaces.
19. The method as defined in claim 18, wherein said motion of said
bristle elements is of an amplitude of vibration to produce a
cavitational action in said fluid film between said bristle
elements and said teeth surfaces when said bristle elements are
displaced therefrom.
20. The method as defined in claim 16, wherein said working end of
said hand-held ultrasonic motor in surrounding relation to said
bristle elements is insulated, whereby the ultrasonic energy waves
arriving at the insulation will be almost totally reflected back
into said instrument providing more energy available to the bristle
elements to perform their work.
Description
BACKGROUND OF THE INVENTION
The field of the present invention resides in an electromechanical
motor system in which the output applicator thereof is made to
vibrate intermittently at an ultrasonic frequency, to produce
bursts of ultrasonic mechanical vibrations repeated at a sonic
frequency. The motor system thus produced is capable of producing
effects characteristic of both ultrasonic and sonic vibratory
devices.
Over the last decade a number of applications have been proposed
and patented in which the introduction of ultrasonic mechanical
vibrations has resulted in new and novel results. Towards this end
the inventors of the present invention have pioneered in the
development of ultrasonic motor-converter systems that could be
manufactured and incorporated into home consumer products
particularly where cost is a major consideration, as well as
dental, medical, and industrial applications and uses. Towards this
end the key consideration has been the development of a low cost
converter-motor system that would permit the application of
ultrasonic energy for use as in an ultrasonic home dental unit,
ultrasonic shaving unit and ultrasonic hobby kit to name but a few.
These and other uses are indicated in the referenced co-pending
patent applications hereinafter referred to throughout the
specification as the "applications" for convenience. A method and
apparatus for the ultrasonic cleaning of teeth is disclosed in U.S.
Pat. No. 3,375,820 which issued on Apr. 2, 1968 to Arthur Kuris and
Lewis Balamuth while an ultrasonic method and apparatus for shaving
is disclosed in U.S. Pat. No. 3,610,080, which issued on Oct. 5,
1971 to Arthur Kuris. The entire subject matter of said Letters
Patent are incorporated herein by reference as if fully set forth
herein.
The present invention provides for the first time a motor-converter
system with a minimum number of electronic components that enables
the manufacture, in the low power range of, for example, from 1 to
10 watts, of instrumentation for home and other use which combines
the beneficial effects of vibrations in the ultrasonic range,
defined herein to include vibrations in the frequency range of
10,000 Hz to 1,000,000 Hz, and in the low sonic frequency range,
defined herein to include vibrations in the frequency range at 10
Hz to 1,000 Hz.
The inventors have discovered that there are many instances where
it is desirable to produce a mechanical vibration which in effect
is a series of high frequency vibration bursts separated by
predetermined time intervals, the separating time intervals being
large compared with the time intervals for a period of the high
frequency vibration. Such mechanical vibration is capable of
producing all the necessary high frequency effect essential to
ultrasonic motor technology. However, the pulsing effect imparts to
the motors' applicator a kind of "jiggling" or "buzzing" effect
during use. Among other advantages to this specific result of the
double frequency system herein described is found in the fact that
the "buzzing" action of the applicator during use gives the user
the psychological assurance that the system is doing its job.
This signalling of the presence of the operating condition of the
device has been found to be necessary in consumer devices such as
hobby kits, razors, toothbrushes and the like using ultrasonic
vibrations for producing their respective operative effects. In the
prior art hand held ultrasonic devices, the user feels no
difference in sensation in the hand holding the device when the
device is on and when the device is off. To be sure, visual aids
may be used, such as a small pilot light, or an auxiliary sonic
device to help the user know the device is on, but such aids add
expense to the device which is unnecessary and is eliminated by the
simplicity of the solution to this problem disclosed herein.
Further, not only is the foregoing problem solved by the
arrangement in accordance with the invention, but further desirable
operative effects are produced in at least some of the ultrasonic
devices in question.
Thus, the arrangement in accordance with the invention produces the
completely unexpected results of a low frequency macro-massage type
action, simultaneously with the ultrasonic micro-massage and other
uniquely ultrasonic effects (due to cavitation, etc.) normally
expected from the ultrasonic devices in question. One of the most
important consequences of the invention is the establishment of a
uniquely new method for applying ultrasonic energy to tissues with
the synergistic benefit of simultaneous micro-massage and
macro-massage.
A further unexpected beneficial result of the method and devices in
accordance with the invention is the dramatic improvements in the
application of ultrasonic energy for periodontal procedures,
primarily for use in the home. Ordinary toothbrushing uses bristles
and tooth paste to keep tooth surfaces clean and hopefully,
polished and bright, a condition usually characterized as "whiten."
In addition, an attempt is made to clean out interproximal,
gingival crest, or gumline areas, and other hard-to-get-at areas
without too much success. Conventional dental teaching requires the
toothbrusher to learn how to stroke the gingival-tooth boundaries
so as to provide some gum stimulation. Electric-vibratory, i.e., 60
cycle per second, toothbrushes attempt to meet all the above goals
with greater efficiency and with the aid of outside electrical
energy to provide additional motion to the bristles during use.
However, such electricvibratory toothbrushes merely utilize the
principles of conventional toothbrushing. Recently, dental science
has recognized the need for the removal of plaque during home
periodontal care as an assist to the professional care ordinarily
supplied by the dentist. However, conventional home cleaning
devices used in a conventional manner fail to remove plaque.
The inventors have discovered that the addition of high frequency
mechanical vibration energy to such elements as bristles or
Stimudents or other applicators permits the removal of plaque,
thereby extending the benefit in oral hygiene normally obtained
from the dentist to safe self-administered procedures followed by
the patient at home. As is usual with high frequency mechanical
vibration devices the benefits are multi-valued comprising the
possibilities of micro-massage, fatigue destruction of calculus,
interproximal cleaning due to cavitational energy in associated
fluids being present, and the like.
The inventors have now found that the utilization of two
frequencies in a vibratory system has produced unexpected
beneficial effects, with each frequency performing its function
such that the cummulative effect of the utilization of two
frequencies exceeds the beneficial effect of either frequency
working in its own frequency range. For example, with respect to
the brushing or cleaning of teeth, it has been established that the
high frequency energy is capable of removing plaque from the teeth
with the low frequency introducing a macro-massage type action both
on the gums and also cleaning teeth with respect to the effect that
the low frequency range provides. Similar benefits are obtained in
the field of shaving where the high frequency of vibratory energy
plays its role as more particularly described in U.S. Pat. No.
3,610,080, and the low frequency component produces its own
beneficial effect.
Aside from the ability for the first time to simultaneously utilize
the beneficial results of two known frequency ranges in a single
instrument, the arrangement and method in accordance with the
invention produces results obtainable due to the combined effect of
the two frequencies. Accordingly, the motor-converter system of the
present invention may be utilized in such a manner that work may be
performed on an object such that it may operate at an ultrasonic
frequency and an audible frequency simultaneously with said
ultrasonic vibrations. Since the current best ultrasonic motor art
requires the vibration frequency of the motor to be at or near one
of the natural vibration resonance frequencies of the motor, the
current invention may use an automatic frequency control feedback
circuit which guarantees a selection of the desired aforementioned
resonant mode.
SUMMARY OF THE INVENTION
Generally speaking, in accordance with the invention, a method for
performing work on a object is provided including the steps of
positioning an applicator capable of physical vibration at an
ultrasonic frequency adjacent the object, inducing vibrations in
said applicator at a frequency in the ultrasonic range and
modulating the ultrasonic frequency of said applicator at a sonic
frequency so as to produce spaced bursts of ultrasonic vibration in
said applicator. To remove foreign matter including plaque and
other surface deposits from teeth, the method in accordance with
the invention would consist of the steps of positioning adjacent
the teeth to be cleaned a plastic surface capable of supporting and
transmitting ultrasonic vibrations, vibrating said surface in
spaced bursts of vibrations in the ultrasonic frequency range, said
bursts being repeated at a sonic frequency, and moving said
vibrating surface relative to said teeth so that it engages and
removes the deposits therefrom. Said surface is in the form of a
plurality of individual bristle elements such that the elements
assume positions in which they are randomly divided between actual
contact with and displacement from the surface of the teeth. A
fluid film may be provided at the teeth surfaces.
Shaving hair by the method in accordance with the invention
includes the step of generating ultrasonic vibrations in the
cutting edge of a blade coupled to a hand-held ultrasonic motor,
applying bursts of ultrasonic vibrations at said cutting edge, said
bursts being repeated at a sonic rate, and engaging said cutting
edge adjacent the hair to be shaved in a relative moving
relationship.
The systems in accordance with the invention include vibratory
means capable of physical vibration at an ultrasonic rate and
driving circuit means electrically coupled to said vibratory means
for applying a driving signal to said vibratory means for
sustaining the vibration thereof, said driving signal consisting of
ultrasonic portions repeated at an audio rate to produce bursts of
ultrasonic vibrations in said vibratory means repeated at said
audio rate. Said vibratory means may include a transmission member
having an output and at which said vibrations are produced and
transducer means physically engaging said transmission member and
electrically coupled to said driving circuit means. Said vibratory
means may define an ultrasonic motor mounted in an ultrasonic
instrument means adapted to be hand held by the user thereof.
Interchangeable means may be provided adapted to be secured to the
front end of the ultrasonic instrument means to permit a variety of
applications of ultrasonic mechanical vibrations to a selected
object for various results. Said interchangeable means may be in
the form of a razor, a toothbrush or the like. The driving circuit
means may include oscillator circuit means for producing a signal
at said ultrasonic frequency and modulating circuit means coupled
to said oscillator circuit means for modulating said ultrasonic
frequency signal at a sonic frequency to produce said driving
signal. Said ultrasonic motor may be capable of vibration at a
plurality of ultrasonic frequencies including a desired frequency,
and said driving circuit means may include tuned circuit means
tuned to said desired frequency for controlling the frequency of
said driving signal and means for applying a detected signal
representative of the frequencies of vibration of said ultrasonic
motor to said tuned circuit means, the tuned circuit means
responding to the desired frequency portion of the detected signal
to cause said driving circuit means to produce a driving signal of
the desired frequency.
OBJECTS OF THE INVENTION
A primary object of the present invention is to provide a variety
of ultrasonic converter systems having both ultrasonic and sonic
frequency characteristics adaptable for both consumer and
commercial use.
Another object of the present invention is to provide an ultrasonic
system wherein bursts of ultrasonic vibrations are produced at an
applicator, said bursts being repeated at an sonic frequency.
Still another object of the invention is to provide an ultrasonic
motor-converter system incorporating interchangeable accessories
permitting a wide variety of uses.
A further object of the invention is to provide a new and novel
ultrasonic motor-converter system.
Still another object of the invention is to provide a new and novel
dual frequency driving circuit for ultrasonic devices.
Another object of the present invention is to provide a new and
novel method of applying ultrasonic mechanical vibrations.
Still another object of the present invention is to provide
improved methods and apparatus for performing oral hygienic
procedures with ultrasonic energy.
A further object of the present invention is to provide novel and
improved cleaning techniques for personal oral hygienic care which
enables the user to control and obtain significantly better
cleaning of teeth.
Still a further object is to provide new and novel methods and
apparatus which are embodied in a device that is completely safe
for use by adults and children in the home on a regular basis.
Another object of the present invention is to provide new and novel
methods and apparatus for regular personal oral hygienic care which
provides excellent cleaning results in the hard to reach
interproximal and gumline areas in general, and simultaneous gum
stimulation.
Still another object of the present invention is to provide
improved cleaning techniques for the removal of plaque, tartar,
calculus, stubborn stains and interproximal soft debris.
Another object is to provide an ultrasonic oral hygene device
providing a sensual indication of its operation during use.
A further object of the present invention is to provide methods and
apparatus employing ultrasonic and sonic energy simultaneously for
shaving of skin and which is completely safe for use in the
home.
Still a further object of the present invention is to provide novel
forms of shaving apparatus and improved shaving techniques
employing sonic and ultrasonic energy in which the frictional
resistance to movement of the shaving instrument over the skin is
substantially reduced.
Another object of the present invention is to provide a novel and
improved shaving technique and apparatus employing sonic and
ultrasonic energy which may be employed with or without a shaving
cream.
Still another object of the present invention is to provide an
ultrasonic shaving apparatus providing a sensual indication of its
operation during use.
Still other objects and advantages of the invention will in part be
obvious and will in part be apparent from the specification and
drawings.
The invention accordingly comprises the several steps and the
relation of one or more of such steps with respect to each of the
others, and the apparatus embodying features of construction,
combinations of elements and arrangement of parts which are adapted
to effect such steps, all as exemplified in the following detailed
disclosure, and the scope of the invention will be indicated in the
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
Although the characteristic features of this invention will be
particularly pointed out in the claims, the invention itself, and
the manner in which it may be made and used, may be better
understood by referring to the following description taken in
connection with the accompanying drawings forming a part hereof,
wherein like reference numerals refer to like parts throughout the
several views and in which:
FIG. 1 is a diagrammatic view of the waves of the ultrasonic
frequency pattern;
FIGS. 2a and 2b are diagrammatic views to illustrate the theory of
the present invention in which two frequency components are
employed;
FIG. 2c is a fragmentary view of an element vibrated in accordance
with the invention and its interaction with a surface;
FIG. 3 is a view of an electrical circuit of the invention to
obtain the dual frequency;
FIG. 4 is a perspective view of an ultrasonic home oral unit in
accordance with the present invention;
FIG. 5 is a front view of the ultrasonic home oral unit in
accordance with the present invention;
FIG. 6 is an end view of the ultrasonic home oral unit in
accordance with the present invention;
FIG. 7 is a side view in cross-section of the ultrasonic home oral
unit in accordance with the present invention;
FIG. 8 is an enlarged sectional view of a portion of the unit in
FIG. 7;
FIG. 9 is an enlarged sectional view of a portion of the unit in
FIG. 7;
FIGS. 10-13 illustrate the cleaning system of the present invention
in relation to a set of human teeth and are helpful in explaining
the process of the instant invention;
FIG. 14 is a view of an electrical circuit similar to that
discussed in FIG. 3 but of another form of the invention;
FIG. 15 is a view of another form of electrical circuit in
accordance with the invention;
FIG. 16 is a perspective view of the invention as used for
shaving;
FIG. 17 is the shaving apparatus in relation to the skin of the
user;
FIG. 18 is a fragmentary side elevational view of the head portion
of a further embodiment of the home oral unit in accordance with
the present invention;
FIG. 19 is an end view of the home oral unit in FIG. 18; and
FIG. 20 is a further side elevational view of the home oral unit in
FIG. 18 with the housing in cross-section.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring to the drawings in detail, and initially to FIGS. 1, 2a,
2b and 2c, the theory relating to the present invention in which
two frequency components are employed in a mechanically vibrating
ultrasonic motor will be described. In the art, ultrasonic
motor-converter systems are generally adapted to produce mechanical
vibrations in the form of a continuous, simple harmonic vibration
of constant amplitude, as depicted in FIG. 11, waveform 10 having a
constant vibration amplitude 11 and a period of oscillation
.tau..sub.2. These ultrasonic vibrations generally lie in the
frequency range including 10,000 Hz to 1,000,000 Hz. One
characteristic of such ultrasonic vibrations is that a solid
surface vibrating at an ultrasonic frequency is actually felt in a
different way than when the surface is not vibrating. During
ultrasonic vibration, friction between the solid vibrating surface
and an object placed in engagement therewith is drastically
reduced, in large measure due to the acceleration of the
vibrations, which in the case of ultrasonic vibrations, is at least
1,000 g.
The inventors have now discovered that in many instances, it is
desirable to produce a mechanical vibration of the type shown in
FIG. 2a, which consists of a series of high frequency vibration
bursts 12 separated by equal time intervals 14, said separating
time intervals being large compared with the time interval 13
representing the period of the high frequency vibration
(.tau..sub.2). As is apparent from an examination of FIG. 2a, the
bursts of high frequency vibration are defined by half sine wave
envelopes, the width of each envelope being equal to time interval
14. Bursts of high frequency vibration 12 are repeated at a sonic
or low frequency having a period .tau..sub.1. For an ordinary 110
volt 60 cycle A.C. source of voltage, .tau..sub.1 would correspond
to one-sixtieth sec. If the natural resonant frequency of the high
frequency vibration is 30,000 Hz, .tau..sub.2 is 1/30,000 sec.
Expressed in microseconds, .tau..sub.2 would equal 33.4 .mu. sec.
and .tau..sub.1 would equal 16,000 .mu. sec. The frequency of
repetition of the bursts of high frequency vibrations lies in the
sonic range, and more particularly between 10 Hz and 1,000 Hz. In
the example given, each burst of high frequency vibration would
include as many as 5,000 complete reciprocations.
It has been found that when an electro-mechanical transducer or
ultrasonic motor is vibrated as indicated in FIG. 2a by bursts or
packets of ultrasonic vibrations, the user experiences a definite
physical sensation when an applicator mounted on said transducer or
motor is engaged against a surface. This sensation, described as
"buzzing" or "jiggling" permits the user to distinguish between the
conditions during which the applicator is on and when said
applicator is off. The drastic reduction in friction caused by
ultrasonic vibrations prevents the experience of any such physical
sensation when a prior art ultrasonic applicator is used. The
"buzzing" or "jiggling" appears to occur at the sonic or low
frequency and is believed to be caused by the difference in the
frictional forces between the applicator and the surface engaged by
the applicator during the bursts of ultrasonic vibration and in the
interval between such bursts. Specifically, during ultrasonic
vibrations, friction between the ultrasonic applicator and the
surface is drastically reduced as compared with the friction during
the interval between said bursts. The resulting, alternating
"slip-stick" effect between the applicator and surface is believed
to cause said buzzing or jiggling. The forces at work when an
applicator is vibrated in accordance with the invention as depicted
in FIG. 2a is indicated by a consideration of FIGS. 2b and 2c. In
FIG. 2b, the lower waveform represents the actual ultrasonic
mechanical vibration of an applicator, such as toothbrush bristle 2
mounted on a vibrating head 3 when engaging against a tooth or
gingival surface 4. The ultrasonic vibrations within each burst is
in the direction represented by double-headed arrow 5.
Each burst of ultrasonic mechanical vibration lasts for a half
period (.tau..sub.1 /2) of the sonic modulation frequency. In an
actual device, during the interval b between bursts the device
would be vibrating at an ultrasonic frequency, but at a very low
amplitude. During interval a, the frictional force of the bristle 2
against tooth 4 is reduced resulting in a slipping action. However,
at the same time, during each individual high frequency
reciprocation there is an impulsive force represented in the upper
waveform of FIG. 2b. This impulsive force pulls on the surrounding
liquid (saliva, mouthwash, dentifrice, or whatever fluid is
present,) and cavitation results. Each returning pushing force in
the liquid causes the cavities to collapse with consequent
production of shock waves. All of this action is rapidly repeated
during intervals a. The dynamics of the force present in interval a
is extremely complex, the representation in FIG. 2b being intended
as schematic and suggestive of the forces present. During intervals
b, we have a relative period of rest, insofar as high frequency
vibration is concerned. The reduction in frequency is dependent on
the presence of relative high amplitude ultrasonic vibrations, the
low amplitude vibrations present during interval b not being
sufficient to reduce the frequency, and a sudden rise in frictional
force occurs. This sudden rise in frictional force is related to
the ordinary brushing force represented by arrow 6 in FIG. 2c which
would be present if the brush were used with no high frequency
vibration at all, and results in the normal displacement of the
brush by the user. This sudden rise in brushing force occurs as the
high frequency vibration force disappears and will continue during
the interval b, which can be characterized as a "stick" interval.
Thus, due to the stick-slip effect of the alternating sonic
modulation of the high frequency vibration, a succession of force
peaks 7 is produced. In effect, this is somewhat like the
introduction of a sonic "tapping" of the tooth gingival structure,
the tapping frequency corresponding exactly to the sonic modulation
frequency (1/.tau..sub.1). Thus, the method and apparatus in
accordance with the invention subject the surface engaged by the
ultrasonic applicator, and in this case, the teeth and gums to a
complex series of dynamic actions incorporating both sonic and
ultrasonic frequencies of energy. During each interval a, an
ultrasonic quanta of energy is applied, while during each interval
b, a peak of energy representative of the brushing force is
applied. Since the brushing force peaks and the ultrasonic quantas
of energy alternate at a sonic rate, it may be said that the method
and apparatus in accordance with the invention produces successive
time periods of high frequency and low frequency effects. As used
herein, the term "simultaneously", as applied to these effects,
merely refers to the fact that during a fraction of a second, both
effects are repeated many times. Thus, for a 100 Hz sonic
modulation frequency, there would be in one-tenth of a second,
thousands of reciprocal high frequency actions and 10 low frequency
actions. It is this unique set of actions which produces the
synergistic results, one of which is the rapid and complete removal
of plaque from teeth including the interproximal regions, together
with macro-and micro-massage of the gingival tissues. A further
effect is the buzzing or jiggling sensation experienced by the
user. In addition, all of the necessary high frequency effects
essential to ultrasonic motor technology are produced during the
bursts of high frequency vibration.
Referring now to FIGS. 3-9, an embodiment 20 of the arrangement in
accordance with the invention is depicted including an instrument
means 25 in combination with driving circuit means 30 that work
together in unison to perform a variety of applications, as for
example that of toothbrushing. The embodiment 20, for example, is
designed to permit daily use by a person in the home of a
toothbrush, the bristles of which are ultrasonically vibrated in
bursts repeated at a sonic frequency. In this embodiment, the sonic
frequency is 60 Hz, and while the toothbrush is effective for the
removal of plaque, which is generally recognized as a principal
source of calculus formation and possible subsequent loss of teeth
due to periodontal disease, and stimulation of the gingiva,
especially at the tooth-gingiva junction regions, the total power
level introduced into bristles 38 is considerably less than 1 watt.
It is noted that the ultrasonic vibration of bristles 38 is
invisible to the naked eye.
Instrument means 25 includes handle means 26 adapted to be hand
held by the user in a conventional manner, and also has a
detachable applicator means or assembly 35 containing a bristle
cluster or stimulent 38 to be ultrasonically vibrated. Extending
from one end of instrument 25 is supply means 32 in the form of an
electrical cable for transmitting power, in the form of a driving
signal from driving circuit means 30 to instrument means 25.
Driving circuit means 30 is mounted within a cabinet 130, and power
for said driving circuit means may be obtained from a standard
electrical outlet (a 60 Hz A.C. source) by means of electrical cord
134 terminating in plug 132. A switching means 40 is mounted on
cabinet 130 consisting of a switch 42 connected in the power line
for the selective energization of the ultrasonic transducer or
motor 45 contained within the housing defining handle means 26.
Supply means 32 consists of a flexible conduit 52, through which
leads 44, 46, 48 and 100 extend. Line 44 is a separate grounded
cable connected to the ground of the electrical outlet plug. The
ultrasonic mechanical vibrations of bristles 38 as indicated by
arrow 41.
Driving circuit means 30 is preferably of the solid state type and
may have a power rating of as small as 1 to 4 watts, and is
generally within the range of 1 to 10 watts. The actual mechanical
power delivered to the bristles and subsequently to the gingiva and
teeth of the user is variable depending on the pressure and
movement of the bristles by the hand of the user. In the case, the
power under maximum conditions is but a minute fraction of the
power delivered to the motor 45.
Essentially, ultrasonic motor 45 as hereinafter described is
designed, depending upon the use thereof, to accept a variety of
applicator means 35 and the magnitude of ultrasonic mechanical
vibrations to be imparted thereto may be selected by proper motor
design. The motor 45 includes a transmission member 50 which has a
rear section 54 and front section 56, which may of circular
cross-section, with a counterbore or seat 58 extending from its
rear face 60 to a bottom surface 62. Mounting means 65 is provided
and includes a radial seat 66 adapted to contain therein means as
in the form of an O-ring 68.
The transmission member 50 has a contoured-radius connecting
portion 70 connecting together the front section 56 and the rear
section 54 of the transmission member 50, which sections may both
be of circular cross-sectional area. The front section 56 extends
out beyond the front end 74 of the tubular housing 72 a sufficient
distance. The motor mounting means, although illustrated to be in
the form of an O-ring 68, may take other forms and shapes as
desired.
The ultrasonic motor 45 in conjunction with the applicator means 35
is longitudinally dimensioned so as to have lengths which are
generally whole multiples of half-wavelengths of the compressional
waves established therein at the resonant frequency of the combined
longitudinal length of the components so that longitudinal loops or
other components of motion occur at the end 78 of the applicator
means 35. Thus, the optimum amplitude of longitudinal vibration and
hyperaccelerations of transmission is achieved, and such amplitude
is determined by the relationship of the masses of the rear section
54 and the front section 56 which may be made effective to either
magnify or reduce the amplitude of the vibrations received from the
transducer crystal. In the usual case, transmission member 50
serves as an amplifier. The front section 56 may be permanently
attached to applicator means 35, or the front section 56, or part
thereof, may be provided with a threaded stud 160 adapted to be
screwed into a tapped hole 162 in the end of the transmission
member 50 for effecting rigid connection of the applicator means
35.
A piezoelectric element such as crystal 80 is mounted within the
cavity means 58 of the rear section 54 and it may be of tubular
shape and in the embodiment shown comprises a lead zirconate-lead
titanate ceramic crystal which is formed so as to be capable of
ultrasonic vibrational activity in its longitudinal direction when
activated by high frequency electrical impulses delivered to it as
will be desired.
The crystal 80 is mechanically joined by a hardening cement 82 of,
for example, the epoxy type which, upon setting, becomes rigid and
provides a solid direct mechanical coupling between the front end
portion 84 of crystal 80 and rear section 54 of transmission member
50 so that ultrasonic longitudinal vibrations of the latter are
directly transmitted to said rear section 54 to form a compound
resonator. As shown in FIG. 9 the rear section 54 has a skirt
portion 86 which extends downwardly over the front end 84 of
crystal 80 and a recessed portion 58 is provided to receive the
epoxy cement 82 to circumferentially surround the front end of
crystal 80.
Crystal 80 is provided with an electrically conductive silver
coating 92 on the inner wall 88 thereof of approximately 0.0015
inch in thickness. Conductive coating 92 may extend along the
entire length of said inner wall 88 or within one-fourth inch of
the end of said inner wall. A similar silver coating is formed on
outer wall 90 of crystal 80, the latter conductive coating being in
two sections, a main section 93 extending along all of surface 90
of crystal 80 except for the end regions thereof, and an annular
portion 96 on the rear portion of outer wall 90, separated from
main portion 93 by a gap 98. Such coatings may be applied by
electro-deposition or any other conventional process. Driving
circuit means 30 is electrically connected with ultrasonic motor 45
by means of leads 44, 46, 48 and 100. Lead 44 is soldered to end
wall 62 of rear section 54 of transmission member 50 to
specifically ground said transmission member. Lead 48 is soldered
to conductive coating 92 while lead 46 is soldered to conductive
coating 93, conductive coatings 92 and 93 cooperating to apply the
driving signal to crystal 80. Finally, lead 100 is soldered to the
annular conductive coating 96, which, together with a portion of
conductive coating 92 defines a oscillation detector means.
A driving signal oscillating at the proper frequency delivered
along leads 46 and 48 to conductive coatings 92 and 93 from driving
circuit means 30 will produce the desired piezoelectric effect and
ultrasonic longitudinal vibration of crystal 80 and applicator
means 35. THe ultrasonic vibrations are created in crystal 80 and
transmitted directly to applicator means 35, so that when bristles
38 are applied to a tooth or other surface to be cleaned, the
vibrations serve to perform the desired cleaning function. The
vibrations are created in crystal 80 by the expansion and
contraction thereof in the longitudinal direction when excited by a
high frequency electrical driving signal. The crystal and
transmission member 50 are specifically designed to be resonant at
a particular frequency, for dental applications, preferably about
35,000 Hz. In fact, the ultrasonic motor depicted does not have a
single natural resonant frequency mode of operation, but rather,
has a whole spectrum of possible modes which include subharmonics
and harmonics of the design operating mode frequency. It is
preferable to design the ultrasonic motor so that it oscillates at
a frequency which will produce the highest Q. The Q at idle is
selected to fall within the strain limits of endurance of the
motor. The motor is further designed for peak efficiency under
load, i.e., when bristles 38 are engaged against the tooth and
gingival surfaces of the user. If the loaded Q drops significantly
below the Q of the other resonant modes of vibration of the
ultrasonic motor, then, under load, the motor will "hop out of
tune" and vibrate at this other frequency. If this occurs, the
device would become ineffective because the motor is not designed
for efficient operation in the new frequency mode. This problem is
solved by the provision of the detecting electrodes defined by
conductive coating 96 and the overlapping portion of conductive
coating 92 and by the design of the driving circuit means 30 as
will be more particularly described below.
Crystal 80 can be electrically energized, if desired, to have
vibratory components in other than the longitudinal direction to
provide various mechanical effects. This would be accomplished by
changing the excitation frequency. In addition, the location of
application of the voltage to the crystal can be utilized to
produce different effects. For example, by applying the voltage
across opposite ends of the crystal, a torsional effect is
produced.
When driving circuit 30 is energized, as by closing power supply
switch 42, the sudden surge of current therefrom will drive crystal
80 into a vibratory mode of operation. The vibrations of crystal 80
will in turn induce vibrations in the detector electrodes so that a
signal representative of the frequencies of vibration of the
ultrasonic motor 45 is transmitted back along line 100 to driving
circuit means 30. As shown in FIG. 3, said circuit includes a
variable inductor 120 and capacitor 106 connected in series with
line 100 to receive the detected feedback signals. Said inductor
and capacitor define a tuned circuit which is tuned to the design
frequency of motor 45 so that, only the portion of the detected
signal at the desired frequency is passed by said tuned circuit. In
effect, the tuned circuit serves as a filter, the filtered signal
of the desired frequency being applied to the base 104 of
transistor 102 which serves to amplify the detected signal. The
emitter 116 of transistor 102 is connected through resistor 118 to
ground while the collector 114 is connected through primary winding
110 of transformer 112 to line 124, which in turn is connected to a
power supply. This power supply consists of the normal A.C. 60 Hz
power supply, which is connected through lines 34 and 36, line 36
being grounded. Line 34 is connected through switch 40 to diode 125
which serves as a half-wave rectifier of the A.C. signal. Lines 34,
36 are coupled by a capacitor 122 which provides D.C. isolation and
some minor smoothing. The resultant, essentially half-wave signal
is applied to line 124 to modulate the ultrasonic frequency
electrical signal applied to the base 104 of the transistor. The
resulting half-wave bursts of ultrasonic oscillation, said bursts
being repeated at a 60 Hz frequency, are applied to lines 46 and 48
through transformer 112 for driving ultrasonic motor 45.
Driving circuit 30 thus serves to sustain the ultrasonic vibrations
of motor 45 within each burst of vibrations at the desired
frequency through the mechanism of the detector electrodes and the
tuned circuit defined by inductor 120 and capacitor 106. Further,
by modulating the ultrasonic frequency oscillating signal by a
half-wave rectified 60 Hz signal, the desired bursts of ultrasonic
vibration are produced. While the embodiment of FIG. 3 depicts a
driving circuit having an A.C. power line as a power source, the
arrangement in accordance with the invention could also be driven
by a battery, in which case a suitable sonic frequency oscillator
circuit would be provided for producing a half-wave signal of a
sonic frequency for modulating the ultrasonic frequency signal
applied to the base of transistor 104.
It will appreciated by one skilled in the art, that the entire
driving circuit means can be formed from about eight components, a
very small number permitting the production of very compact and
light weight driving circuits. The precise values of the respective
components depends on the power output of the device. But, as
illustrated in FIG. 4, the driving circuit may be mounted in a
relatively small housing 130. The components may easily be
contained in a rectangular area having the dimensions 1 1/2 .times.
2 .times. 1 1/2". Switching means 40 mounted on said cabinet
permits the user to selectively turn the toothbrush on or off as
desired. Not only does the foregoing construction reduce size, it
substantially reduces the cost thereof to the point where a
consumer product becomes feasible. As shown particularly in FIG. 7,
housing 72 may be injection molded or formed in an acceptable
manner and includes a rear section plug 136 that fits in telescopic
relation with the housing 72 and having an aperture 138 extending
axially therethrough for receiving flexible conduit 52 of supply
means 32 to retain said flexible conduit in fixed position relative
to plug 136. A clip 140 is positioned around conduit 52 to retain
the latter such that the user cannot apply any tension on leads 44,
46, 48 or 100 during use of the instrument. A pin 142 is seen to
extend through the wall of handle housing 72 and into a pocket in
plug 136 so as to retain the latter in fixed position. Various
means may be used for this purpose. To retain the motor 45 in fixed
position relative to the housing 72, retaining means 145 may be
employed. As seen particularly in FIG. 9 the retaining means may
include a dowel or pin 146 that extends transversely through the
housing wall 144 and into a pocket or seat 148 contained within the
rear section 54 of the transmission member 50 so that the latter
remains in fixed position relative to the housing 72 when the user
either initially secures the applicator means 35 to the instrument
means 25 or removes it therefrom. Obviously, other forms of
retaining means may be employed to maintain the coupled
relationship so that rotational movement is prohibited between the
transmission means 50 and the housing 72.
As seen particularly in FIG. 9, the front end 74 of the housing 72
may have a lip 150 that blends with the connecting portion 70 of
the transmission member 50. Mounting means 65, which also includes
0-ring 68, also acts to seal the inner chamber of the handle means
26 from any fluid that might try to seep into the instrument during
use by the user.
Applicator means 35 may take various forms, shapes and
configurations, so long as it is designed so that the complete
system will operate in tune whether the instrument is out of
engagement with any surface, such as in the air, or in engagement
with a surface which may be the oral cavity of the user or may be
the face of the user where the applicator means is a shaving
device. The apparatus in accordance with the invention is
particularly adapted to maintain the combined ultrasonic
motorapplicator means vibrating at the desired frequency at various
load conditions, and to modulate such vibrations so as to produce
bursts of ultrasonic vibrations. It is the ability to obtain and
maintain this vibratory condition with the combination of
electronic circuitry and ultrasonic motor which is a particular
feature of the present invention.
The applicator means 35 in this embodiment of the invention is
illustrated as an ultrasonic toothbrush which is more fully
disclosed and described in a simultaneously filed co-pending patent
application assigned to the assignee of the present invention and
entitled "Ultrasonic Toothbrush Applicator," Ser. No. 318,430 which
may be referred to for a more detailed discussion of a form of
brush applicator that may be used in connection with the present
invention and reference thereto may be had for information, but by
no means limitation thereto. Essentially, the brush applicator
includes a body portion 152 having a plurality of bristle clusters
38 extending therefrom at substantially right angles thereto and
terminating prior to the end face 78. The body portion 152 merges
with a neck portion 154 and terminates at an end face 156. Coupling
means 160 is provided for proper transmission of the ultrasonic and
sonic vibratory energy from the end of front section 56 of
transmission member 50. Said transmission member has an axially
extending tapped hole 162 which receives therein a threaded stud
164 which merges with a flange portion 165, which in turn has a
threaded portion 166 extending from the opposite end thereof in
axial alignment with the threaded stud 164. The threaded portion
166 may be firmly secured within complimentary threads 168
contained within the body portion 154, a bonding agent 170 being
provided therebetween to help couple the energy between threaded
portion 166 and the body portion 154. If coupling means 160 is
injection molded in combination with the plastic applicator means
35, then the bonding agent can be dispensed with since an intimate
coupling between the two threads is obtained and sufficient energy
transmission is realized to properly transmit energy to vibrate the
bristle clusters 38 which in turn produce the vibrating motion in
accordance with the invention. The flange portion 165 may be of a
cross-sectional area such as hexogonal to permit ready grasp by
either mechanical means such as a wrench or by the hands of the
user to assure that the bottom face 172 is in intimate contact with
the output end or front face 61 of the output section. An axial
bore 174 may be provided, if required, as to control the total
cross-sectional area of the body portion 154 so as to obtain the
proper transmission of vibratory energy to the head portion 152 and
in turn the bristle clusters 38.
To provide a protection for flange portion 165 and the body portion
154, a sleeve 175 may be shrink fitted as seen in FIG. 9 to
properly encompass the material which it covers. The sleeve 175 may
be of a plastic material and may also act as insulation.
Turning now to FIGS. 10-13, there is illustrated a portion of the
dental cleaning procedure in accordance with the invention in
operative position in the oral cavity 178 against the teeth
180.
The brush construction may be that which resembles closely an
ordinary manually actuated toothbrush or designed more particularly
as set forth in the co-pending patent application entitled
"Ultrasonic Toothbrush Applicator" hereinabove referred. In
accordance with the invention, the brush bristles 38 of the
applicator means 35 is positioned against the teeth 180 in the
usual manner during the brushing operation. That is, the bristle
clusters 38 are inserted in the mouth and positioned adjacent the
tooth surfaces 183 with a relatively light pressure. The bristle
clusters 38 may be moved manually to pass the brush portion across
all of the tooth surfaces, the bristles 38 randomly assume
positions in contact with and displaced from tooth surfaces. Since
in the case of manual brushing, the bristle elements 38 rarely
assume positions such that they extend deeply into the
interproximal areas 185 the present brush is designed to
approximate the curvature thereof.
In this manner the action between the sonic motion and ultrasonic
motion is believed to result in a combination effect such that the
beneficial features of each frequency is simultaneously
obtained.
Accordingly, the removing of plaque 181 on the tooth surface 183
and foreign deposits 182 are obtainable with the present invention.
In FIG. 10 plaque is shown as a coating that has adhered to the
surfaces of the teeth 180. Plaque, a soft gelatinous substance
produced in the mouth by the action of salivary and sub-gingival
bacteria, hardens into calculus in a period of from 2 to 12 days,
and is believed to be a significant factor in causing periodental
disease.
In use, the bristle clusters 38 are vibrated in accordance with the
invention so as to introduce a micro-motion and a macro-motion as
described above. When bristle elements 38 are lightly engaged
against the teeth surface 183 and a relative moving relationship is
maintained there is generated sufficient action to remove the
plaque 181 and interproximal deposits 182. This action is generally
obtained by providing a fluid film as illustrated by the particles
184 which may be in the form of a dentifrice having certain
characteristics such as mild abrasive characteristics, water or
simply that of saliva. The ultrasonic motion at the bristle
elements 38 is of sufficient amplitude of vibration to also produce
a cavitational action in the fluid film 184.
In addition, the present invention permits stimulation of the
gingival tissue by macro-massage and micro-massage which has been
found beneficial for dental health, said massage also resulting in
more blood circulation than is obtained by conventional brushing
techniques. In addition, the stick-slip effect produces a sonic
audible vibration due to the tapping of the bristles against the
teeth which helps the user psychologically by communicating to him
the fact that the instrument is working.
The angular positioning of bristle clusters 38 with respect to the
applicator means 35 is substantially normal to the longitudinal
mode of vibration, but this relation can be varied. Further, the
ultrasonic vibration applied to applicator means 35 may be other
than a pure longitudinal vibration. Thus, a radial mode of motion
may be applied to said applicator means. Furthermore, the length
and stiffness of the various bristles may be varied within the
confines of the present invention and beneficial results may still
be obtained.
The bristle elements 38, as seen particularly in FIG. 13, may have
a contoured surface configuration that lead themselves to conform
to the contour of teeth 180 such that the bristle elements form a
surface consisting of a multiple number of pointed members
interproximately of the teeth during the brushing thereof which
produces peak accelerations in the bristle elements.
One aspect of the present invention is to provide an insulated
coating 186 that may surround the toothbrush head 152 to improve
efficiency in that the coating 186 may be of a material which
prevents transmission of high frequency vibratory energy into
liquid, teeth or gums. This is readily accomplished, for example,
with a closed cell rubber sheet 186. The closed cell layer 186
presents to the vibrating surface an acoustic impedance equivalent
to that of an air film. The acoustic impedance of air is so
mismatched, i.e., so much smaller than the acoustic impedance of
the brush head plastic 152 that all ultrasonic energy waves
arriving at the brush head-closed cell interface will be almost
totally reflected back into the plastic thereby making more energy
available to the bristle clusters 38 to do their work.
Referring to FIGS. 18-20, the instrument 220 depicted differs from
the instrument depicted in FIG. 3, in that a cowling or hood 222
extends about the sides, rear and end of applicator means 35 so as
to prevent engagement of said applicator means with the cheak or
jaw of the user. Cowling 222 is formed integral with housing 224 as
more particularly shown in FIG. 20.
Referring now to FIG. 14, the system 20a depicted is essentially
identical with the system of FIG. 3, except that driving circuit
30a is provided with a resistor 120a in place of variable inductor
120. This construction assumes that the ultrasonic motor 45 is
designed so as to be stable in its frequency of operation when
subjected to normal loads experienced in toothbrushing, so that the
tuned circuit arrangement of FIG. 3 is not required. In all other
respects, the arrangement of FIG. 14 is identical to the
arrangement of FIG. 3.
Referring now to FIG. 15, a further type of driving circuit and
ultrasonic motor combination is depicted. The ultrasonic motor is
provided with a pair of crystals 188b and 189b having an electrode
190 therebetween. Motor 45b further includes a rear portion 190b
and locking means in the form of a nut 192b for holding rear
portion 191b, crystals 188b and 189b and electrode 190b in
compressed engagement with transmission member 50b. Driving circuit
30b is coupled to motor 45b by lines 204b and line 203b. Line 203b
is electrically connected to electrode 190b while line 204b is
grounded and connected to rear portion 190b. This embodiment does
not have a crystal detector arrangement for sustaining the motor at
the desired frequency. Rather, the frequencies of oscillation of
motor 45b are reflected back through lines 204b and 203b to driving
circuit 30b where they are detected for the purposes of controlling
the frequency of the driving signal applied to said motor for
collector the vibrations thereof. Driving circuit 30b includes a
transistor 205b. The emitter 216b of said transistor is connected
through resistor 217b to ground. Resistor 217b is shunted by a
capacitor 218b. The collecgor 206b of said transistor is connected
through choke 207b to variable resistor 199b, which in turn is
connected to the power source. The junction between collector 206b
and choke 207b is connected through capacitor 215b to line 204b and
is connected to the primary winding 202b of transformer 212b, the
other end of said primary winding being connected to line 203b. The
secondary of transformer 212b is connected in parallel with a
capacitor 214b to define a tuned tank circuit. Said
parallelconnected circuit is connected between ground and the base
209b of the transistor. Said base is also connected through
resistor 208b to resistor 199, for biasing said base.
The power supply is connected to the normal A.C. 60 Hz source
through lines 34b and 36b, and in turn is applied to the primary
winding 198b of transformer 195b. The secondary winding 196b of
said transformer is coupled between ground and a diode 194b. The
parallel combination of a capacitor 197b and resistor 193b is
connected between said diode and ground, resistor 193b being tapped
off and connected to resistor 199b. Said power supply produces a
half-wave rectified signal, the value of capacitor 197b being
selected for minimum smoothing.
Driving circuit 30b operates as follows. When switch 42b is closed,
a surge of energy is applied to crystals 189b and 188b and the
motor 45b is set into oscillation. A signal representative of the
frequencies of oscillation of said motor is reflected back through
lines 204b and 203b to the primary of transformer 212b. This signal
is detected by the tuned circuit defined by secondary winding 210b
and capacitor 214b, which is tuned to the desired frequency of
oscillation of the motor. Only the portion of said detected signal
representative of said desired frequency is transmitted to base
209b to switch transistor 205b on and off at an ultrasonic rate.
When transistor 205b is on, the power signal from the power source,
essentially in the form of a half-wave rectified signal, is short
circuited. When transistor 205b is off, the power signal is applied
through transformer primary winding 202b to the ultrasonic motor.
In this manner, a driving signal consisting of bursts of ultrasonic
oscillations repeated at a sonic rate are applied to motor 45b to
produce bursts of ultrasonic vibrations repeated at a sonic
rate.
Turning now to FIGS. 16 and 17, there is illustrated a shaving
system 20c which is described in greater detail in the co-pending
patent application assigned to the assignee of the present
invention, Ser. No. 204,632, filed Dec. 3, 1971, and for present
purposes, it is sufficient to indicate that it includes an
instrument means or handle means 25c adapted to be held by the user
in a conventional manner, with a detachable shaving head or
assembly 221c containing a member or blade 223c to be
ultrasonically vibrated and mounted therein. Extending from one end
thereof is supply means 130c which supplies to the instrument means
25c, power from generator or power means 30c having an electrical
cord 134c connected to a plug 132c adapted to be plugged into a
standard electrical outlet; i.e., 60 cycles per second. Switching
means 40c on the generator includes a switch 42c for providing
power for energizing the ultrasonic transducer or motor 45c
contained within the instrument casing or housing means 26c of the
hand-held instrument 25c. The energy from the generator 30c is
transmitted to the ultrasonic motor by wires extending through the
flexible conduit 52c of the supply means 32c.
The complete assembly for use in the home includes the generating
means 30c, for example, a transistorized driving circuit means
capable of producing a driving signal consisting of bursts of
electrical oscillation at a frequency in the ultrasonic range, as
defined herein, repeated at a sonic rate herein defined. Driving
circuits to obtain the dual frequency are discussed in detail with
respect to FIGS. 3, 14 and 15.
The ultrasonic energy available at the cutting edge 225c of the
blade 223c provides several beneficial results. It has been found
that, by reason of the vibrations at the cutting edge 225c, which
vibrations may be in a substantially vertical plane; that is, in a
plane perpendicular to the plane of the cutting edge 225c, the
resistance of the blade member 223c across the skin surface is very
substantially reduced. The friction reduction effects and the
cutting ease may be obtained by the vibrations having an
elliptical, orbital, longitudinal or flexural component of motion
at the cutting edge 225c. A possible explanation of this observed
phenomenon is that the extremely high acceleration of the cutting
edge 225c of shaving member 223c resulting from the vibrations
causes only a relatively small sliding friction to be present
between the engaged skin surface and the shaving member 223c. Thus,
the dual frequency provides a visible gross motion to the shaving
member 223c and simultaneously imparts to the shaving member the
acceleration forces to reduce the friction and successively subject
the hair portions extending from the skin to the cutting action of
the cutting edge at a repetition rate of from 15,000 to 500,000
times per second and thus provide a continuous severing of the
hairs at or adjacent to the surface of the skin.
The frequency of the vibrations at the free end portion of blade
member 223c is in the range from 15 to 500 kilocycles per second,
while the amplitude of the vibrations is selected within the range
from approximately 0.0001 to 0.025 inch so as to ensure the
introduction of vibratory energy sufficient to perform the cutting
of the hair particles and maintain the friction reduction
qualities. Simultaneously therewith, the convertermotor system
functions by cyclically interrupting the vibratory motion to
produce the buzzing or jiggling which indicates that the razor is
operating.
Thus, the vibratory energy applied at a suitable frequency, to the
blade produces vibratory motion of the molecular structure of such
blade so that the surface of blade 223c is continuously maintained,
while being moved relative to the hair, at a state of microscopic
motion in the ultrasonic range relative to the surface of the skin,
whereby the frictional resistance of movement of the shaving member
223c to the surface is determined by the kinetic coefficient of
friction therebetween rather than by the substantially larger
static coefficient of friction between the material of the shaving
member 223c and the skin. The ultrasonic shaving instrument 20c
also permits a closer shave to be obtained due to the inherent
characteristics of a vibratory member which when vibrated in the
ultrasonic frequency range as herein defined will vibrate with an
acceleration of at least 1,000g's such that the time of contact
between the cutting edge 225c and the surface of the skin is
minimal even when a static force is applied by the user against the
skin.
Due to the geometric configuration of the mounting of the blade
223c within the shaving head assembly 22c, it is possible to obtain
a flexural component of motion at the blade edge 225c and at the
same time the physical vibration produced by the ultrasonic
frequency produces peak accelerations in the shaving member of the
order of at least 1,000g. The ultrasonic frequency may be in the
range of 20 KHz to 60,000 KHz and the low sonic frequency in the
range of 0.01KHz to 0.10 KHz. Low guard edge 232c is designed to
function in conjunction with blade edge 225c in effecting shaving.
The ultrasonic vibrations are introduced in a longitudinal
direction, and due to the geometry of the shaving head assembly
221c, the vibrations are induced in blade 223c in a plane
substantially normal to the surface thereof.
CONCLUSION
From the foregoing, it will be evident that the application of
bursts of ultrasonic vibrations repeated at a sonic rate is
effective to provide significantly improved results in many
applications of vibratory motion, only two of which have been
herein illustrated by way of example. It is well appreciated that
the invention herein defined may be employed in innumerable
applications, some of which presently exist in the form of low
frequency applications and others in the form of high frequency
applications, so that for the first time, the synergistic benefits
of the combination of high and low frequency effects may be
achieved.
It will thus be seen that the objects set forth above, among those
made apparent from the preceding description, are efficiently
attained and, since certain changes may be made in carrying out the
above method and in the devices set forth without departing from
the spirit and scope of the invention, it is intended that all
matter contained in the above description and shown in the
accompanying drawings shall be interpreted as illustrative and not
in a limiting sense.
It is also to be understood that the following claims are intended
to cover all of the generic and specific features of the invention
herein described, and all statements of the scope of the invention
which, as a matter of language, might be said to fall
therebetween.
* * * * *