Note: Descriptions are shown in the official language in which they were submitted.
W092/1368~ 21 !) 1 i `;`, PCI/I,'S91/09601
THERMALLY ASSIS~ED SHAVING SYSTE~I
FIELD O,P_~E I~IVENTIO~J
The present invention relates generally to devices
which cut hair. More particularly, the present invention
relates to shaving devices which shave the hair on the
surface of skin. The present invention is particularly,
though not exclusively, useful for shaving hair on a
surface of skin without requiring wètting or
pre-lubrication of the skin.
BACKGROUND OF TH~ INVENTION
Many devices exist for removing hair from a skin
surface. Among the most common of these devices is the
safety razor which cuts hair by means of a very sharp
razor blade. Unfortunately, sharp blades can produce
undesirable results, such as nicking and cutting of the
skin. Therefore, in order to reduce nicking and
irritation, a lubricating solution, such as soap and
water or shaving cream, must typically be applied to the
skin prior to shaving. This can be inconvenient and,
unfortunately, does not completely eliminate nicking or
other forms of skin irritation. On the other hand, a
dull blade, though perhaps less likely to nick or
irritate skin, cannot cut hair, under ordinary
circumstances, as efficaciously as a sharper blade.
To avoid skin irritation problems and the
inconveniences noted above that are associated with
so-called "wet" shaving, a number of devices have been
introduced which remove hair without the use of a razor
blade. For example, hair depilation devices have been
proposed which remove hair by heating or by irradiating
the hair follicles. The principle of these devices is
that as hair is heated, it becomes softer and easier to
remove from the skin. Unfortunately, in order to remove
hair solely by heating the hair, a relatively large
amount of heat must be directed onto the hair. These
relatively large amounts of heat must be precisely
controlled to avoid injuring the skin. The requirement
for precise control of the heat results in hair
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WO92/136W ~ , r`~ PC~/~S91/09~1
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depilation devices which are relatively expensive and
which typically require an expert operator. Accordingly,
inexpensive, simple, easy to use devices such as safety
razors are still preferred. The present invention
recognizes that a relatively dull razor blade which is
less likely to nick or cut the skin than a relatively
sharp blade can be used to shave hair by exposing the
hair to a relatively small amount of heat to soften the
hair immediately before the hair is cut by the blade.
It is therefore an object of the present invention
to provide a shaving system which uses a razor blade to
cut hair, but which does not require prelubrication of
the skin. It is a further object of the present
invention to provide a shaving system which cuts hair
without requiring prelubrication of the skin and without
requiring an expert operator. Another object of the
present invention is to provide a shaving system which is
easy to use and comparatively cost-effective to
manufacture.
SUMMARY
A device for shaving hair includes a housing which
is formed with a handle and which supports a cutting
blade and a means for heating the hair to be cut. The
heating means is a source of electromagnetic radiation,
preferably a laser, or a source of infrared radiation,
such as a metallic heating element. More specifically,
in the preferred embodiment a laser generating apparatus
may be mounted in the housing to scan and focus a laser
beam onto the hair near the cutting edge of the blade.
~he laser generating apparatus itself has a source
of laser light. The laser beam produced by the source is
passed through optical collimating components and
subsequently directed onto a scanning mirror. The
scanning mirror is oscillated by a galvanometric scanner
to linearly scan the laser beam onto a lens. As the beam
is scanned onto the lens in a line across one face of the
lens, the angles of incidence of the beam relative to the
lens vary along the line of incidence. In accordance
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with the present invention, the lens is configured to
refract the beam, which is incident on the lens at
various angles along the length of the line, such that
the beam exits the lens in parallel paths. Next, the
beam is passed through a focussing blade, which focusses
the beam in a line a few microns distant from the blade.
This line is near the cutting edge of the razor blade and
is substantially parallel to the cutting edge of the
blade.
Alternatively, the laser apparatus may be dispensed
with and another source of radiated heat, such as a
nickel-chromium element which is electrically heated, may
be mounted in the housing near the cutting edge of the
blade. The heating element may be formed with a bevelled
edge through which heat will preferentially be
dissipated. The heating element is positioned in the
housing so that its bevelled edge is close to and
parallel with the cutting edge of the razor blade.
Importantly, hair which is heated by the laser or heating
element is thereby softened and made easier to cut.
Thus, a blade that is less sharp than conventional razor
blades may be used.
To energize the laser apparatus or heating element,
as appropriate, a battery may be contained in the
housing. On the other hand, appropriate electronic
componentry may be included in the housing to transform
power from an electrical outlet into an energy form which
is useful for energizing the laser or heating element.
The novel features of this invention, as well as the
invention itself, both as to its structure and its
operation, will be best understood from the accompanying
drawings, taken in conjunction with the accompanying
description, in which similar reference characters refer
to similar parts, and in which:
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is an isometric view of the novel thermally
assisted shaving device;
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W092/l~ 3 3 PCT/~'S91/09601
Figure 2 is a cross-sectional view of the preferred
embodiment of the novel thermally assisted shaving device
as seen along the line 2-2 in Figure 1;
Figure 3 is a cross-sectional view of an alternate
embodiment of the novel thermally assisted shaving device
as would be seen along the line 2-2 in Figure l; and
Figure 4 is a schematic view showing the operable
laser components of the preferred embodiment of the
shaving device with the housing of the device shown in
phantom for clarity.
DESCRIPTION OF TH~ PREFERRE~ EMBODIMENT
Referring initially to Figure 1, a thermally
assisted shaving device is shown and generally designated
10. As shown, device lO includes a cutting blade 12 and
a laser focussing blade 14, both of which are fixedly
held in an electrically resistive ceramic housing 16. A
switch 18 is also shown operatively mounted in a handle
20 of the housing 16 for selectively energizing and
deenergizing device lO. Figure 1 further shows that
device lO may be energized by a power supply 22, which
may be either a direct current (dc) or alternating
current (ac) source of power. Power supply 22 is
connected to device lO through electrical cord 24. While
Figure 1 shows that device 10 is energized by an external
power supply 22, it is to be understood that the present
invention also envisions use of a dc power supply, such
as a battery (not shown), which may be contained within
the housing 16 to energize device lO.
The details of device lO are best seen in reference
to Figure 2. There, housing 16 is shown to include a
detachable ceramic blade cartridge 26, which fixedly
holds blade 12. Blade cartridge 26, like housing 16, may
alternatively be made of rubber or plastic. As shown,
cartridge 26 has tongues 27 extending therefrom for
engagement with grooves 17 of housing 16. It is to be
appreciated that tongues 27 are engageable with grooves
17 in an interference fit. Accordingly, blade 12 may be
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WO92/13~W PCT/~S9l/~60l
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replaced by replacing cartridge 26 with a new cartridge
which also contains an appropriate razor blade. If
desired, however, housing 16 could be a single integrated
unit in which blade 12 is permanently mounted or,
alternatively, is individually replaceable.
Still referring to Figure 2, blade 12 is m~unted in
cartridge 26 by any suitable means, such as by solvent
bonding blade 12 to cartridge 26. As shown, blade 12
defines a cutting edge 28, which protrudes from cartridge
26 for the purpose of cutting hair 11. Because the hairs
to be cut by blade 12 are to be softened by preheating,
as disclosed below, cutting edge 28 of blade 12 can be
relatively less sharp than the cutting edges of
conventional blades. Specifically, in the embodiment
shown in Figure 2, width 34 of cutting edge 28 is
approximately on the order of a hundred microns.
Finally, Figure 2 shows that housing 16 also
contains the focussing blade 14 of a laser apparatus
which will shortly be disclosed. Blade 14 may be held in
housing 16 by any suitable means, such as by solvent
bonding b~ade 14 to housing 16 or by attaching blade 14
to housing 16 with screws (not shown). The device shown
in Figure 2 focusses a linearly scanned laser beam,
represented by dashed lines 60, onto a heating line which
in its end view is represented by the dot 44 in Figure 2.
Laser beam 60 heats hair 11 prior to shaving the hair 11
with blade 12. To this end, heating line 44 is
substantially co-planar with cutting edge 28 of blade 12,
and is preferably but a few millimeters distant from
cutting edge 28 to minimize heat loss from hairs which
have been heated by beam 60 prior to the hairs being cut
by blade 12.
In the alternate embodiment of device 10 shown in
Figure 3, focussing blade 14 has been replaced by a
heating element 15. Element 15 is made of an
electrically resistive material, which grows hotter when
electricity is passed through it. In the preferred
embodiment, element 15 is made of a nickel-chromium
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WO 92/13684 2 J ~J ~ j PCr/~:S91/0961)1
~NiCr) alloy. Importantly, heating element 15 may be
heated through wire 30, which is connectable to the power
supply 22 shown in Figure 1 to heat the hairs and stratum
corneum of the skin to be shaved. As also shown in
Figure 3, heating edge 32 of element 15 protrudes from a
housing 50. A razor blade 46 which has a cutting edge 48
also protrudes from housing 50. Blade 46 is in all
essential respects identical to the blade 12 shown in
Figure 2. ~lade 46 may be integrally attached to housing
50 or removably mounted in housing 50, or be part of a
replaceable cartridge 52 that is attachable to housing
50.
Importantly, in order to increase the radiated heat
from element 15 near cutting edge 48, heating edge 32 may
be bevelled or rounded, as shown in Figure 3. As is
well-known, heat is preferentially dissipated through
such a bevelled, or thinner, portion of element 15
because such a portion is relatively electrically more
resistive than other thicker portions of element 15 and
will accordingly dissipate relatively more heat than the
relatively thicker portions. Moreover, the distance 36
between cutting edge 48 and heating edge 32 is preferably
relatively small. For purposes of the present invention
distance 36 is on the order of a few millimeters. This
is to ensure that as device 10 passes over a surface of
- skin (not shown) in the direction of arrow 38, the
heating effect of blade 46 is optimized. Specifically,
the closer heating edge 32 is to cutting edge 48, the
less heat will be lost from hairs that are heated by
heating element 15 before the hairs are cut by blade 46.
The details of the heating laser of the device shown
in Figure 2 can be best appreciated in reference to
Figures 2 and 4. It is to be understood that the
following disclosure is merely exemplary of one laser
apparatus which may be used with device 10. Other types
of laser apparatus which can produce a linearly scanned
laser beam and which are suitable for use with device 10
may also be used.
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WO92/13~ PCT/~S91/~601
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Cross-referencing Figures 2 and 4, it is to be
understood that a laser beam, represented by arrow 54 in
Figure 4, is emitted by any suitable laser beam source
56. Laser beam source 56 may be any one of a number of
laser beam sources including a YAG laser, a carbon
dioxide (Co2) laser, or a diode laser which emits a laser
beam having an approximate wavelength of 840 nanometers
(nm). A diode laser which emits a beam of approximately
840 nm is preferred because such a beam is more readily
absorbed by hair than by skin. Importantly, to
facilitate dexterous use of device lO, it is preferable
that source 56 be relatively small and light weight.
In any case, laser beam 54 is optically coupled to
collimator 58 by fiber optic lines (not shown) or by
line-of sight. Collimator 58 is any suitable device
which transmissively or reflectively collimates laser
beam 54. The shape and size of the beam 60 as it exits
collimator 58 will vary according to the particular
source 56 and collimator 58 being used. For example, if
collimator 58 transforms incident laser beam 54 into a
coherent pencil beam, beam 60 will have an approximate
diameter of between two and three millimeters. It will
be understood that independent of the type of collimator
58 or laser source 56 being used, collimator 58 may be an
integral component of laser source 56. In addition,
collimator 58 and laser source 56, whether they are
separated or joined as a single integral unit, may be
housed in either power supply 22 or housing 50, as
desired.
After being collimated by collimator 58, the laser
beam 60 is directed against a scanning mirror 62. In the
embodiment shown in Figure 4, laser beam 60 is first
reflected by a folding mirror 64 onto the scanning mirror
62. For the embodiment shown in Figure 4, the mirrors 62
and 64 are preferably both low mass, thin reflectors of
the standard quarter-wave or half-wave variety. In
addition, the reflecting surfaces 66 and 68 of mirrors 62
and 64, respectively, are coated with a reasonably high
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092/1~W PCT/~S91/09601
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reflectivity coating, the thickness of which depends on
the particular wavelength of laser light being used. As
is well known in the art, such coating increases the
light reflectivity coefficient of laser beam re~lectors
and lenses. As is also well known, such a coating may
have one or more layers of coating material.
As further shown in Figure 4, scanning mirror 62 is
fixedly attached to a shaft 70, which is in turn
rotatably mounted for oscillating motion on a scanner 72
for purposes more fully disclosed below. Scanner 72 may
be any suitable device for oscillating shaft 70 (and,
hence, scanning mirror 62) at an appropriate frequency
and through an appropriate scanning angle. In
particular, the embodiment shown in Figure 4 contemplates
the use of a suitable commercially available
galvanometric scanner 72. Depending on the potential
needs for the operation of device lO, scanner 72 may be
of the resonant type (i.e., single oscillation
frequency), for simpler electronic componentry
requirements, or may be a servo controlled galvanometric
scanner. Such a servo controlled scanner provides a
capability to vary scanner 72 oscillation as appropriate
for particular device lO stroke speeds across the surface
to be shaved. In either case, the method of coupling
scanning mirror 62 with scanner 72 should substantially
prevent translational motion of scanning mirror 62
relative to scanner 72. Such translational displacement
between scanning mirror 62 and scanner 72 will result in
a failure to achieve a parallel scan, as well as increase
beam aberrations at the skin surface.
As contemplated by the present invention, scanner 72
provides for substantially rotational-only motion between
scanner 72 and scanning mirror 62. Scanner 72 does this
by oscillating scanning mirror 62 about an axis 74 of the
shaft 70 in the directions indicated by arrow 76. As
seen in Figure 4, scanning mirror 62, when appropriately
oscillated by scanner 72, causes the laser beam 60 to
move back and forth through orientations that are
w092/1~ PCT/US91/~ ~1
9 2~J ~ 3
variously indicated by the lines 80. This causes beam 60
to impinge on a scan lens 82 in a line 78.
It will be appreciated in reference to Figure 4 that
the scanned beam 60, as represented by the lines 80,
impinges on lens 82 at various angles of incidence 84
along the line 78. Moreover, it will be further
appreciated in reference to Figure 4 that the lens 82 is
disposed within device lO such that the rear focal point
86 of lens 82 is substantially coincident with a portion
of surface 66 of scanning mirror 62 which lies on axis
74. It will now also be understood that scanner 72
oscillates scanning mirror 62 through an arc which is
appropriately sized for the focal length 88 and width 90
of lens 82.
As disclosed above, the scanned beam 60 which is
reflected from scanning mirror 62 along lines 80 is
continuously changing its orientation relative to lens
82. Accordingly, the function of lens 82 is to refract
beam 60 from the non-parallel orientations at which it is
incident on lens 82 so that scanned beam 60 exits lens 82
along substantially co-parallel lines 96. It is
therefore to be appreciated that the particular material,
dimensions, and shape of lens 82, which establishes light
refraction characteristics of lens 82, will vary
according to the particular wavelength of the laser beam
produced by source 56. For most wavelengths of scanned
beam 60, lens 82 has a width 90 which is approximately
one and one-half (l.5) inches long. Additionally, lens
82 has a depth 92 approximately one-quarter (0.25) inches
long, and a breadth 94 approximately one-half (0.5) inch
long. As was the case for reflecting surfaces 66, 68 of
mirrors 62, 64, respectively, lens 82 is thinly coated
with an anti-reflection coating to minimize energy loss
from scanned beam 60.
Still referring to Figures 2 and 4, it may be seen
that scanned beam 60 emerges from lens 82 in
substantially co-parallel paths as indicated by lines 96.
It will be appreciated by the skilled artisan that by so
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w092/l~w PCT/US91/~601
aligning~h~ ~re~ously divergent paths of scanned beam
60, lens 82 facilitates maximum transmission of laser
light energy into and through focussing blade 14. As
seen in Figure 4, the focussing blade 14 is a relatively
flat focussing lens which directs the laser energy that
is incident on line 100 of face 102 onto focusing line
44, shown in Figure 2.
As shown in Figure 4, the breadth 104 of focussing
blade 14 is approximately one and one-guarter (1.25)
inches long. Moreover, in order to focus the laser beam
60 as it is directed along co-parallel scanned lines 96,
faces 102, 106 of blade 14 are convex. In addition,
while focussing blade 14 may be made of any material
suitable for focussing beam 60, focussing blade 14 is
preferably sapphire. It will be understood that as was
the case with lens 82, selection of the particular
material of focussing blade 14 will depend in part on the
wavelength of the laser beam which is generated by source
56. Moreover, focussing blade 14 may be coated on
selected portions of its exterior surface (i.e. surfaces
108 and 110) with a high durability anti-reflection
coating, to enhance the light transmission
characteristics through blade 14.
OPERATION
In the operation of thermally assisted shaving
device 10, reference is initially made to Figures 1, 2
and 3. After electrical connections are made with
appropriate power supplies, device 10 may be energized by
3~ depressing switch 18 to complete the electrical circuits
in device 10. For the embodiment shown in Figure 3,
heating element 15 is thereby energized with electricity
and accordingly dissipates the electrical energy as heat.
Device 10 may then be positioned against the surface to
be shaved and moved across the surface in the direction
of arrow 38. Consequently, hair which is adjacent
heating edge 32 of heating element 15 is heated and
softened for easier cutting by blade 46. More
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WO 92/13684 PCr/US91/09601
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specifically, heating element 15 pre-heats and thereby
softens hair along heating edge 32 prior to the hair
being cut by blade 46. This makes the hair easier to
cut, which in turn permits the use of a relatively less
sharp blade 46.
In the operation of the embodiment of device 10
shown in Figures 2 and 4, it can be seen that upon
energizing device 10, the laser source 56 generates the
laser beam 54, which is transformed into the collimated
10 beam 60 by collimator 58. Upon emerging from collimator
58, beam 60 is reflected by folding mirror 64 onto
scanning mirror 62. In accordance with previous
disclosure, scanning mirror 62 is oscillated at an
oscillation frequency in the range 100-200 Hz by
15 galvanometric scanner 72 to scan beam 60 along the lines
80 onto lens 82. The now-scanned beam 60 is refracted by
scan lens 82 into co-parallel paths 96, and is thus
directed by lens 82 onto incident edge 102 of focussing
blade 14.
Beam 60 is subsequently focussed into line 44 as it
passes through blade 14. More specifically, as beam 60
emerges from blade 14, it is focussed along the line 44
to a diameter of a few microns. Thus, when device 10 is
positioned adjacent the surface to be shaved, beam 60
25 preheats and thereby softens hair along line 44 for
easier cutting of the hair by blade 12. This makes the
hair easier to cut, which in turn permits the use of a
relatively less sharp blade 12.
While the particular thermally assisted shaving
30 device as herein shown and disclosed in detail is fully
capable of obtaining the objects and providing the
advantages herein before stated, it is to be understood
that it is merely illustrative of the presently preferred
embodiments of the invention and that no limitations are
35 intended to the details of construction or design herein
shown other than as defined in the appended claims.
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