Note: Descriptions are shown in the official language in which they were submitted.
W0~5133600 ~ ~ 2 1 ~ 1 7~ 1 PCTIGK9~101220
HAIR CUTTING APPARATUS
.
FIELD OF THE INVENTION
The present invention relates to shavers gener-
ally and more particularly to radiation operative shav-
ers .
BACKGROU~D OF THE INVENTION
Laser operative shavers have been proposed in
the patent literature. The following references are
believed to represent the state of the art in the patent
literature.
U.S. Patents 1,378,137; 1,720,775; 3,093,724;
3,1g7,612. 3,538,g19; 3,659,613 3,693,623; ~,83~,391,
3,934,115; 4,051,760; 4,089,110; 4,388,924; 4,578,558;
4,608,978; 4,617,926; 4,819,669; 4,819,6~9; 5,037,183;
5,038,015; 5,043,553; 5,065,515; 5,05g,192; 5,079,402;
5,093,549; 5,182,857; 5,226,907; Published PCT patent
applications WO 91~06406; WO 92~16338; WO 93~05920;
British Patent 2,123,287; Canad~an Patent 1,041,610;
French Patent 2,590,7g1; German Patent 3,220,962.
SUBSrIME SHEET (RULE 26~
wo gsl33600 2 ~ ~ ~ 7 5 1 pcTlcs9~/ol22o
SUMMARY OF THE INVE~TION
The present invention seeks to provide improved
halr cutting apparatus.
There is thus provided in accordance with a
preferred em~odiment of the inventlon, hair cutting
apparatus including:
a housing;
a source of non-coherent light disposed in the
housing; a hair entry opening defining in the
housing for permitting hair to be cut to enter the hous-
ing; and
optics directing the non-coherent light from
the source of non-coherent light along a hair cutting
pathway adjacent the hair entry opening for cutting the
hair.
There is also provided in ~rror~nre with a
preferred embodiment of the invention hair cutting appa-
ratus including:
a housing;
a source of coherent light disposed in the
housing;
a hair entry opening defining in the housing
for permitting hair to be cut to enter the housing; and
optics directing the coherent light from the
source of coherent llght along a hair cutting pathway
adjacent the hair entry opening for cutting the hair
into plural pieces, such that a portion of the hair
remains attached to skin of a user and another part
remains intact and separated therefrom.
Preferably, the hair cuttlng apparatus includes
a moustache trimmer disposed in the housing.
In accordance with a preferred embodiment of
the present invention the hair cuttlng apparatus also
Lncludes a cut hair receptacle remova~ly disposed within
the housing.
wo9sl33fino ~ 2 ~ 9 ~ 7S ~ PCr/lJB9~/01220
Preferably, the halr cutting apparatus also
~ includes a fluid pump disposed within the housing for
providing a fluid flow which draws cut hairs into the
receptacle. The fluid pump also preferably provides a
fluid flow directed at the optics for maintaining at
least a portion of the optics clear of spurious matter.
Additionally, the fluid pump also preferably provides a
fluid flow directed at either or both the light source
and the optics for cooling thereof.
The fluid pump is preferably powered by an
electric motor which preferably also powers the mous-
tache trimmer.
The hair cutting apparatus preferably also
includes electronic control circuitry governing the
operation of the source. Preferably, the electronic
control circuitry includes at least one detector for
determining correct orientation of the light and wherein
the electronic control circultry is operative in the
absence thereof, for modifying or terminating operation
of the source.
In accordance with a preferred embodiment of
the present invention, the electronic control circuitry
includes at least one detector for determining the exist-
ence of operative contact between the housing and a
user's skin and wherein the electronic control circuitry
is operative in the absence thereof, for modifying or
terminating operation of the source.
Preferably, the hair entry opening defines a
plurality of hair entry apertures. In accordance with one
emho~ir-nt of the invention, the hair entry apertures
are formed with tapered side walls arranged such that
light from the source impinging thereon is not reflected
thereby outside of the housing.
In one Pmho~r?~t of the invention, the hair
entry opening is located at a location along the housing
having a radius of curvature in at least one plane which
~ ~;
~95/3360U ~ ~ - 2 1 ~ 1 7~ I PC~/GBg~0l22~1
is smaller than that the radii of curvature of at least
most of the remainder of the housing.
Preferably, the hair entry opening includes at
ieast one portion having a thickness which is less than
the thickness of at Least most of the remainder of the
housing.
Preferably, the hair cutting apparatus com-
prises optics which is operative to provide a beam of
light lmpinging on hair to be cut for cutting thereof,
the beam having a width which exceeds its height along
the hair cutting pathway.
In accordance with a preferred embodiment of
the present invention, the beam and the hairs are ori-
ented such that the beam may simultaneously impinge upon
multiple hairs along its width and that the extent of
its impingement on each hair is approximately e~ual to
thc height of the beam.
Preferably~ the hair cutting apparatus also
includes light source operating circuitry for causing the
source to emit light in a plurality of relatively short
high energy pulses. Preferably, each of the relatively
short high energy pulses is confLgured to produce an at
least partially rounded hair stump.
In accordance with a preferred embodiment of
the present invention, the hair cutting apparatus in-
cludes a receptacle includes an air permeable filter
having odor absorbing capability. Preferably, the recep-
tacle includes an entry passage which is configured to
prevent cut hairs from readily exiting the receptacle
therethrough.
In accordance with a preferred embodiment of
the present invention, the entry apertures are formed
with tapered side walls arranged to assist in lifting
hairs into cutting engagement with the pathway.
There is also provided in accordance with a
preferred embodlment of the present invention a hair
WO95,'33600 2 ~ Sl PCT/GB9S/01220
cutting method comprising:
~ providing a source of non-coherent light dis-
posed in a housing having a hair entry opening for per-
mitting hair to be cut to enter the housing; and
directing non-coherent light from the source of
non-coherent light along a hair cutting pathway adjacent
the hair entry opening for cutting the hair.
There is additionally provided in accordance
with a preferred embodiment of the present invention a
hair cutting method comprising:
providing a source of light disposed in a
housing having a hair entry opening for permitting hair
to be cut to enter the housing; and
directing non-coherent llght from the source of
non-coherent light along a hair cutting pathway adjacent
the hair entry opening for cutting the hair into plural
pieces, such that a portion of the hair remains attached
to skin of a user and another part remains intact and
separated therefrom.
Preferably, the above-describes methods also
include providing a fluid flow which carries out at least
one of the following functions: draws cut hairs into the
receptacle, maintains at least a portion of the optics
clear of spurious matter, and cools at least one of the
light source and the optics for cooling thereof.
Preferably, the method also includes determin-
ing correct orientation of the light and in response to
the absence of correct orientation, modifying or termi-
nating operation of the source.
Preferably, the method also includes determin-
ing the existence of operative contact between the hous-
ing and a user's skin and in the absence thereof, modify-
ing or terminating operation of the source.
Preferably, the method also includes causing
the source to emit light in a plurality of relatively
short high energy pulses.
: = :
w09s~33~ /~D~ ~122U
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BRIEF DESCRIPTION OF THE DRAWI~GS
The present invention will be understood and
appreciated more fully from the following detailed de-
scription, taken in con~unction with the drawings in
which:
Figs. lA, lB and lC are pictorial illustrations
of shaviny apparatus constructed and operative ln accord-
ance with a preferred embodiment of the present lnven-
tion;
Pig. 2 is a generalized illustration o~ the
optical, electronic and mechanical elements employed in
the shaving apparatus of Figs. lA - lC;
Figs. 3A, 3B and 3C are generalized illustra-
tions of the optical apparatus employed in the shaving
apparatus of Figs. lA - lC in accordance with three
alternative embodiments of the present invention;
Figs. 4A and 4B simplified iLlustrations of
part of the shaving apparatus of Figs. lA - 3C;
Figs. ~A and 5B are partially cut away illus-
tratlons o~ the shaving apparatus of Figs. lA - lC in
respective shaving and non-shaving orientations;
Fig. 6 is a partial lllustration of a hair
engagement portion of the shaving apparatus of Figs. lA -
lC in hair ensagement;
Figs. 7A and 7B are sectional illustrations
taken along lines A - A and B - B respectively in Flg. 6;
Fig. 3A is an illustration of an undesired
theoretical construction, such as could be taken along
line VIII-VIII of Fig. 6, showing limits of angular
regions for beams impinging thereon;
Figs. 8B, 8C and 8D illustrate beam paths for
various beams for the undesirable construction shown in
Fig. 8A;
Fig. 9A is a sectional illustration typically
taken along line A - A of Pig. ~, showing limits of
WO95/33600 ~ ~ ~ 2 ~ ~ ~ 7 ~ ~ ~CT/GF95/01220
angular regions for beams lmpinging th~ereon for a deslred
construction;
Figs. 9B and 9C illustrate beam paths for
various beams for the emhodimpnt of Fig. 9A; Fig.
10 is a simplified illustration of a laser beam used for
cutting hair in accordance with a preferred embodiment of
the present invention;
Fiy. 11 is a simplified illustration of a
Gaussian distribution of energy of the laser beam of Fig.
10;
Figs. 12A and 12B are illustrations of relative
portions of th.e energy of a laser light beam in the
embodiment of Fig. 10 which are permitted to escape the
enclosure via the hair entry apertures 152 for different
disposition angles of walls of the hair entry apertures;
Figs. 13A and 13B are illustrations of relative
portions of the energy of a non-coherent light beam in
the embodiment of Fig. 10 which are permitted to escape
the enclosure via th.e hair entry apertures 152 for dif-
ferent disposition angles of walls of the hair entry
apertures;
Fig. 14 illustrates a rounded top edge of a
hair entry aperture in accordance with a preferred embod-
iment of the present invention;
Fig. 15 is an illustration of a preferred
construction of a hair engagement portion including a
hair entry aperture in accordance with a preferred embod-
iment of the present invention;
Figs. 16A and 16B are illustrations of a possi-
ble shaver construction arrangement;
Figs. 17A and 17B are illustrations of a pre-
ferred shaver construction arrangement;
Pigs. 18A and 18B are illustrations of another
preferred shaver construction arrangement; Fig.
19A is an illustration of a preferred cutting beam ar-
rangement which also includes plural beam detectors;
W09513~ 2 i 9 ~ 7 5 ~ PCTIGB95/0122~
Pig. 19B lS an illustration of a preferred
cutting beam arrangement which also includes plural beam
detectors sensing an auY.iliary test beam;
Fig. 20 is an lllustration of the provision of
a skin contact detector in a shaver in accordance with a
preferred embodiment of the present invention;
Fig. 21A and Fig. 21B together provide a flow
chart illustration of the operation of a shaver employlng
the sensors of Figs. 19~, l9B and 20;
Fig. 22 is a sectional illustration of part of
a shaver housing constructed and operative in accordance
with a preferred embodiment of the present invention;
Fig. 23 is a simplified illustration indicating
typical cross sectlonal dimensions of a hair cutting beam
used in the present invention in relation to hairs to be
cut;
Figs. 24A, 24B and 24C lllustrate various
stages in hair cutting in accordance with one embodiment
of the present invention;
Figs. 25A and 25B illustrate various stages in
hair cutting ln accordance with another Pmho~im~nt of
the present invention;
Figs. 26A and 26B are timing diagrams which
illustrate two alternative embodiments of pulsed laser
operation particularly useful in the present invention;
and
Figs. 27A and 27B are simplified electrical
schematic illustrations of two alternative ~mho~ nts of
electronic circuitry useful in the embodiment of Fig. 20.
~og~/33~00 PCT/GB95l01220
~ ' 2 ~ 9 1 7 5 ~
, ~
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
.
Reference is now made to Figs. lA, lB and lC
which illustrate a radiation operative shaver constructed
and operative in accordance with a preferred embodiment
of the present invention. The shaver comprises a housing
which defines adjacent a first end 12 thereof a hair
entry opening 14 and adjacent a second end lS thereof an
air outlet opening 16.
The shaver preferably includes a mechanical
moustache trimmer 18, as well as an operator controlled
three position switch 20, which enables the user to
select OFF status (0), radiation shaving only (1) or
moustache trimming only ~2).
A whisker collection receptacle is indicated at
reference numeral 22. Malfunction warning indicators 24
and 26 may also be provided.
Reference is now made to Fig. 2, which illus-
trates in general the optical and mechanical elements
employed in the shaving apparatus of Figs. lA - lC. A
light source 40, which may be a coherent light source,
such as a diode laser, or a non-coherent light source,
such as a Zirconium arc lamp, a Xenon arc lamp or a
halogen lamp, directs a beam of light via a collimator
lens 42 and a plurality of lenses 44 to a folding prism
46 which directs the beam along a hair cutting path 48
adjacent and generally parallel to hair entry opening 14.
~ hen a non-coherent light source is employed,
the energy efficiency thereof may be r~imi7P~ by design-
ing it such that it either emits a parallel beam which is
collected by the optical assembly downstream thereof.
Alternatively the light source may provide a converging
beam which may be focussed by the optical assembly into a
suitable beam shape for hair cuttins. Either possibility
may be achieved by suitable positioning of reflecting
mirrors and/or lenses having positive power as integral
~'0 135133600 PCT/G139~,'01220
: ~ 2 ~ q 7 75 ~ --
parts of the light source, taking into account the posi-
tion and design of the lamp filament.
In accordance with one embodiment of the inven-
tion, the path 48 may terminate at a termination element
50. Termination element 50 may be a beam absorber and
may include a detector. Alternatively, the beam absorber
may be replaced by a reflecting element which is opera-
tive to reflect the beam and thus provide a multiple-
traversal hair cutting path. Under certain clrcum-
stances, it may be necessarily to provide a flow of
pressurized air to termination element 50 in order to
keep it free of debris. This may be accomplished in a
manner similar to that shown in Fig. 2 for prism 46.
The reyion traversed by hair cutting path 48 is
partially enclosed by a removable enclosure 52 which
forms part of receptacle 22 ~Fig. lBj. Coupled to the
interior of enclosure 52 is an inlet 53 to a vacuum pump
54 which is controlled by control electronics 56 and
which causes cut halrs and other debris to he drawn lnto
engagement with a filter 58 disposed within enclosure 52
and preferably away from hair cutting path 48.
~ he vacuum pump 54 proviaes two air outputs.
One such output ls supplied via an air cleaning filter 60
to the region ad~acent prism 46 for blowing away cut
hairs or other debris therefrom and for maintaining
positive air pressure along the opticaL path between the
light source 40 and the prism 46, thereby to reduce
ingress of contaminants thereto. A second air output is
supplied to the region adjacent light source 40 and
collimating lens 42, for cooling thereof. The second air
output is vented through air outlet opening 16 ~Figs. lB
and lC).
Control electronics 56 will be described here-
inbelow in greater detail and is at least partially
responsive to inputs from various detectors along path 48
for governlng the proper operation of the light source 40
W095l33600 PCTIC,B95101220
~ 1 q 1 7 5 1
11
and the vacuum pump 54.
Reference is now made to Fig. 3A whlch illus-
trates the optical elements employed in the shaving
apparatus of Figs. lA - lC when a coherent light source
80, such as a gallium arsenide diode laser, is employed.
The coherent light source 80 directs a beam of light via
a collimator lens 82 and a plurality of cylindrical
lenses 84 to a folding prism 86 which directs the beam
along a hair cutting path 88 adjacent and generally
parallel to hair entry opening 14.
In accordance with one emho~ir?rt of the inven-
tion, the path 88 may terminate at a beam absorber 90,
which may include a detector. Alternatively, beam absorb-
er 90 may be replaced by a reflecting element which is
operative to reflect the beam and thus provide a multi-
ple-traversal hair cutting path.
Reference is now made to Fig. 3B, which illus-
trates the optical elements employed in the shaving
apparatus of Figs. lA - lC when a non-coherent light
source 100, such as a Zirconium, Xenon or halogen light
source, is employed.
In this ~mho~ -nt the light source 100 directs
a beam of light via a plurality of lenses, indicated for
example by reference numerals 102, 103, 104 and 105.
These lenses are preferably either coated or colored so
as to provide filtering to a plurality of narrow bands,
such as, for example, the bands in the near InfraRed (IR)
region between 750 nm and 980 nm, in the visible region
between 480 nm and 680 nm, and in the Ultra Violet (UV~
region between 330 nm and 480 nm. The actual filtered
bands may have a Full Width At Half Maximum (FWHM) band
width typically less than lOnm.
For example lenses 102, 104 and 105 may be
either coated or colored so as to absorb light of given
wavelengths and lens 103 may be coated so as to reflect
light of another given wavelength. Any other suitable
WO 9~133600 P~l/GB95/012~0
2 ~ q ~ ~5 1
12
combination of lenses having absorption and/or reflectlon
properties may alternatively be employed.
The flltered light output from light source 100
is reflected ~y a folding prism 106 which directs the
beam along a hair cutting path 108 adjacent and generally
parallel to hair entry opening 14. Alternatively filter-
ing may be achieved by employing a discrete filter in
addition to the lenses 102 - 195.
It is noted that the filter coatings on the
lenses 103 are operative to reflect light away from the
lenses and into the interior of housing 10. This provides
a relatively efficient heat dispersion result and pre-
vents localized overheating of individual optical ele-
ments or particular regLons of the housing 10.
Reference is now made to Pig. 3C, which illus-
trates another embodiment of the optical elements em-
ployed in the shaving apparatus of Figs. lA - lC when a
non-coherent light source 120, such as a Zirconium, Xenon
or halogen light source, is employea.
In this ~ho~ir-nt the light source 120 directs
a beam of light via a collimator lens 122 and a plurality
of lenses 124 which are not coated to provide filtering
as in the embodiment of Fig. 3B. Substantially the tota~
light output from light source 120 is reflected by a
folding prism 12~ which directs the beam along a hair
cutting path 123 ad~acent and generally parallel to hair
entry opening 14.
Reference is now made to Figs. 4A and 4B, which
are simplified illustrations of part of the shaving
apparatus of Figs. lA - 3C. Fig. 4A illustrates a remova-
ble cut hair receptacle assembly employed in accordance
with a preferred embodiment of the present invention.
The assembly of Fig. 4A includes a removable
receptacle 130 including an end wall 132 having formed
thereon a protrusion or recess 134 for enabling it to be
grasped by a user and pulled out of the shaver housing
, .. , . . , .. . _ . _ . . _ . . , . . , . . , _ . . _ _
W O 95133600 2 1 9 ~ 7 5 1 P(~rIGB9S/01220
10. Aside from the end wall 132, the receptacle 130 may
be formed of an air porous mesh 135, which is reinforced
by ribs 136. The end wall 132 may be separable from the
mesh 135 to enable easy emptying of the receptacle.
Alternatively, any other suitable emptying arranqement
may be made. A microswitch 133 is preferably provided to
sense removal of the receptacle 130 and to disable shaver
operation when the receptacle is removed. Air porous mesh
135 may also be operable to absorb unpleasant odors from
the hair cutting operation and is preferably operative to
absorb, rather than reflect, light beams which may inad-
vertently impinge thereon. Mesh 135 typically functlons
as the filter 58 described generally with reference to
Fig. 2.
A pair of walls 137 and 138 define an entry
passage 139 communicating with the hair entry opening 14
of shaver housing 10 for receiving cut hairs. The walls
137 and 138 are inclined so as to prevent, insofar as
possible, most of the cut hairs from exiting the recepta-
cle 130 via the entry passage 139, as will be described
herein in connection with Figs. 5A and 5B.
Receptacle 130 is slidably engageable within
enclosure 52 (Fig. 2) and mesh 135 preferably defines
filter 58 mentioned above in connection therewith.
Pig. 4B illustrates mechanical apparatus for
operating the moustache trimmer 18 (Fig. lB). The appara-
tus includes a clutch 140 which includes a first clutch
plate 141 which is fixed to an output shaft 142 of motor
and a second clutch plate 143 which is coupled via a
shaft 144 to an eccentric drive element 145, which en-
gages a cam 146 in a moustache cutting blade 147. Blade
147 is thus driven in vibratory motion indicated by
arrows 148 relative to a static blade 149.
Second clutch plate 143 is coupled to three
position switch 20 by a connecting element 151, for
selectable operation of the moustache trimmer 18.
WO9~l336~ ~ ~ PCTtGR9~/0l22(\
~1 9~ 751
14
Reference is now made to Figs. 5h and 5B, which
are partially cut away illustrations of the shaving
apparatus of Figs. lA - lC in respective shaving and non-
shaving orientatlons. It is seen that during shaving,
shown in Fig. SA, cut hairs enter the receptacle 130 via
entry passage 139. When the shaver is oriented in a non-
shaving orientation, as shown in Fig. 5B, the inclined
orientation of walls 137 and 138 prevents most of the
hairs from èxiting the receptacle 130 via the entry
passage 139.
Fig. 5A also illustrates how the vacuum gener-
ated by the pump 54 (Fig. 2~ draws the hair bearing skin
surface into the hair entry opening 14.
Reference is now made to Figs. 6, 7~ and 7B
which are illustrations of a preferred ~ho~ t of a
hair engagement portion 150 of the shaving apparatus of
Figs. lA - lC, defining hair entry opening 14 ~Fig. lA).
The hair engagement portion 150 defines a multiplicity of
hair entry apertures 152, one of whlch is shown in hair
engagement. A typical principal direction of movement of
the shaving apparatus relative to the skin of a user, is
indicated by an arrow 153.
It may be appreciated that the configurations
illustrated in Pigs. 7A and 7B are intended to assist in
lifting hairs into cutting engagement with the beam and
straightening the hairs such that they are cut as close
to the skin as possible. It is seen that the ang~es B and
C along which the sides 154 of the hair entry apertures
152 are disposed, may differ from each other along the
periphery of the aperture, as indicated by Figs. 7A and
7B. Alternatively, the apertures may be formed with
conical walls.
Reference is now made to Pigs. 8A - 8D which
show a undeslrable structure for the halr engagement
portion shown in Fig. 6. Fig. 8A is a sectional iLlustra-
tion taken along line VIII-VIII of Pig. 6, showinq limits
., . . _ . . .... . . . . . .
wo g5/33Goo ! ~ 7 ~ .h~r!0l220
of angular regions for beams impinglng thereon.
Angle A1 is given by the following expression:
A1 = arctan 0.5h/L
Angle A2 is given by the following expression:
A2 = arctan h/L
where L is the longitudinal opening parallel to the beam
axis;
and h is the thickness of the hair engagement portion,
as shown in Figs. 8A - 8~.
It is seen that in the undesirable structure
illustrated in Figs. 8A - 83, the side walls of hair
entry apertures 150 are perpendicular to the plane of the
hair engagement portion.
In the illustrated structure, all light which
travels towards an aperture side wall lS4 in a direction
which is at more than 90 degrees with respect to the side
wall 154 eventually passes outside of the enclosure
defined in part by the hair engagement portion.
Figs. 8A and 8C show that a light beam imping-
ing on side wall 154 at an angle A4 between angles A1 and
A2 with respect to the perpendicular to side wall 154 is
reflected off side wall 154 and exits the enclosure.
Fig. 8B shows that a light beam whose direction
lies at an angle A3, which is greater than angle A2,
exits the enclosure without impinging on side wall 154.
Fig. 8D shows that a light beam whose direction lies at
an angle A5, which is less than A1 but greater than 90
degrees with respect to side wall 154 undergoes multiple
reflections from the side walls but eventually exists the
enclosure.
Reference is now made to Figs. 9A - 9C which
show a desirable structure for the hair engagement por-
tion shown in Fig. 6. Fig. gA is a sectional illustration
taken along line VIII-VIII of Fig. ~, showing limits of
angular regions for beams impinging thereon.
Ar.gle B2 is given by the following expres-
w09~/336~0 ~ ~ pcT~Gss~lol~2o
7 5 1
16
sion:
B2 = arctan k/D
where W is the longitudinal opening parallel to the beam
axis at the outside surface of the hair engagement por-
tion;
k is the thickness of the hair engagement portion,
as shown in Figs. 9A - 9C;
T is inclination angle after each individual open-
ing;
and D is the distance indicated in Fig. 9A.
It is seen that in the desirable structure
illustrated in Figs. 9A - 9C, the side walls 162 and 164
of hair entry apertures 150 are tapered towards each
other from the interior of the housing to the exterior
thereof.
Flgs. 9A and 9B show that a light beam directed
towards side wall 162 at an angle B3 greater than B2
exits the enclosure without impinging on side wall 162.
Fig. 9C shows that a light beam whose direc~ion
lies at an angle s4, which is less than angle B2 is
reflected off side wall 162 back towards the inside of
the enclosure.
In accordance with a preferred embodiment of
the present invention the opposite side wall 164 of each
hair entry aperture may be angled at an opposite but
equal angle to that of side wall 162, but one which
tapers towards the opposite side wall from the interior
of the housing to the exterior thereof. Thus, if a beam
impinges upon ~ide wall 164 in directions opposite to
those described hereinabove in connection with side wall
162, equivalent results will be achieved.
Further in accordance with an embodiment of the
present invention, the hair entry apertures may be con-
figured to have conical side walls, such that their
angular configuration is identical along any section
taken perpendicular to the plane thereof.
W095~33600 ~ 9 ~ 7 ~ ~ PCI/~. !01220
.
~ eference is now made to Pigs. 10 - 12B which
illustrate, not necessarily to scale, the laser beam used
for cutting hair and the Gaussian distribution of enersy
thereof.
Fig. 10 shows in a generalized form the cutting beam
270 which is typically reflected from prism 46 (Fig. 2).
P is shown as the distance between the reflected optical
axis of the beam at its intersection with prism 46 and
the internal surface of the hair engagement portion and J
is shown as the distance from the above point of inter-
section to the furthest opening in the hair engagement
portion.
Fig. 11 illustrates the Gaussian energy distri-
bution of beam Z70 at a given location along beam 270.
It may be seen from a consideration of Fig. 12A that for
a laser beam when T is less than or equal to 0 in the
context of Figs. 9A - 9C, (e.g. the example of Figs. 8A -
8D) a substantial portion of the energy is allowed to
exit the enclosure. If T is selected to be greater than
0, however, as indicated in the example of Figs. 9A - 9C,
only approximately 10-6 of the energy is permitted to
exit the enclosure, as indicated in Fig. 12B.
By a consideration of Figs. 12A and 12B, it is
seen that the energy indicated in the Gaussian between
angles G and B2 is prevented from exiting the enclosure
by virtue of the inclined orientation of the walls of the
hair entry aperture 152, as shown in Figs. 9A - 9C.
Referring now to Figs. 13A and 13B, it may be
seen that for a Zirconium, Xenon or halogen light beam
even when T is less than or equal to 0 in the context of
Figs. 9A - 9C, (e.g. the example of Pigs. 8A - 8D) a
substantial portion of the energy is not allowed to exit
the enclosure. If T is selected to be greater than 0,
however, as indicated in the example of Figs. 9A - 9C,
substantially no energy ls permitted to exit the enclo-
sure, as indicated in Fig. 13B.
~,~.'O 95~33600 ~ 7 5 I PCIIG~9~101Z20
18
Reference is now made to F1g. 14 which sllus-
trates a preferred ~mho~ll nt of the top edge 280 of the
hair entry aperture 1~2. As lllustrated in Fig. 14, it lS
preferred that the portion of the top edge 280 along
which a beam 232 may impinge tangentially be rounded, so
as to minimize diffraction which would occur were the
edge to be sharp.
Fig. 15 illustrates a preferred configuration
of a hair engagement portion 300 which is characterized
in that the regions defining hair entry apertures 302 are
raised inwardly away from the skin of the user, designat-
ed by reference numeral 304. This configuration enables a
relatively smooth shaving surface to be presented to the
user~s skin while maintaining the desired angle T of the
side walls 306 of the hair entry apertures 302. Alterna-
tively, a hair engagement portion may be provided defin-
ing hair entry apertures which are raised outwardly
towards the skin of the user.
Reference is now made to Figs. 16A and 16B,
which are illustrations of a possible shaver construc-
tion arrangement. The configuration of Figs. 16A and 16B,
which is not preferred, locates a hair engagement portion
320 at a portion of the housing 322 having a relatively
large radius r1 which is identical to the general radius
R1 which extends over a relatively large area of the
- housing.
Using this configuration, it is relatively easy
for a user to position the housing incorrectly with
respect to his skin, indicated by reference numeral 324,
such that the hair engagement portion 320 is not optimal-
ly located with respect thereto, as exemplified in Fig.
16B. An ideal orientation of the hair engagement portion
320 is shown in Fig. 16A, where the plane of the hair
engagement portion lies perpendicular to the skin surface
324.
Reference is now made to Figs. 17A and 17B
WU9~/33600 PCTIGB9~,'01220
T 7 ~ T
1~
which are illustrations of a preferred shaver construc-
tion arrangement. Here the area surrounding a hair en-
gagement portion 340 has a smaller radius r2, as compared
with the radius R2 of the lower portion of the corre-
sponding housing 342. Using this configuration, improper
positioning of the housing with respect to the skin
surface 344, does not space the hair engagement portion
significantly away from the skin surface as in the embod-
iment of Fig. 17B. Furthermore, the relatively small
radius of the housing adjacent the hair engagement por-
tion 340 enables the hair engagement portion to be
pressed against and into the skin surface 344 so as to
maintain reasonably good shaving engagement therewith.
Reference is now made to Figs. 18A and 18B,
which are illustrations of another preferred shaver
construction arrangement. Here the area surrounding a
hair engagement portion 360 has an even smaller radius
r3, as compared with the radius R3 of the lower portion
of the corresponding housing 362. Using this configura-
tion, improper positioning of the housing with respect to
the skin surface 364, does not space the hair engagement
portion significantly away from the skin surface as in
the embodiment of Fig. 18B. Here, the very small radius
of the housing adjacent the hair engagement portion 360
enables the hair engagement portion to be readily pressed
against and into the skin surface 364 so as to maintain
reasonably good shaving engagement therewith.
Reîerence is now made to Fig. l~A, which is an
illustration of a preferred cutting beam arrangement of
the type shown in Fig. 2, which also includes plural beam
detectors. An input radiation beam 380 is principally
reflected by a prism 382 to define a cutting beam 384
which travels generally parallel to a hair engagement
portion 386 and impinges onto a radiation beam detector
388. A relatively small part of the energy of radiation
beam 380 is not reflected by prism 382 but is reflected
WO ')~33600 PCT/GB9!;101~20
21 ql 75~ ~--
hy a downstream prism 390 and is focussed by lenses 392
onto a second detector 394.
The purpose of providing plural detectors is to
verify proper beam delivery from the light source to the
prism independently of verification of proper orientation
of the cutting beam 384. Thus, if proper beam delivery i5
indicated but proper orientation of the cutting beam 384
is not, an indication may be given to the user that
cleaning of the vicinity of the hair engagement portion
386 is required. Furthermore, and perhaps more impor-
tantly, if proper beam delivery is not lndicated, the
shaver may be disabled until it is serviced by an author-
ized person.
Reference is now made to Pig. 19~, which is an
illustration of a preferred cutting beam arrangement
which also includes plural beam detectors sensinq an
auxiliary test beam. The auxiliary test beam is provided
by means of an auxiliary light source 400 such as a
GaAlAs or InGaAsP LED, for example a ~odel SDL-2380,
manufactured by Spectra-~iode Labs ~SDL~ of San Jose,
California, U.S.A., and associated optics 402 and a beam
splitter 404 and enables the integrity of the imaging
optics of the device to be confirmed before a high energy
beam is directed therealong. In this case the detectors
and detector optics are chosen to correspond to the test
beam and are indicated respectively by reference numerals
389, 395 and 393. In this case, sensor 389 is preferably
operative to absorb only the light from auxiliary light
source 400 and is operative to reflect high intensity
light from the cutting beam, so as not to be damaged
thereby.
Fig. ~0 illustrates the use of a skin contact
sensor 410 in a shaver. The sensor 410 operates in con-
~unction with sensor electronics 412, which forms part of
electronics 56 ~Fiq. 2) T~o alternative embodiments of
electrical circuitry forming part of the sensor electron-
~OgS~3600 PCT/GB9S101220
2 ~ '~ 1 7 5 1
21
ics 41Z are illustrated in Figs. 27A and 27B.
Referring now to Pig. 27A, there is shownelectronic circuitry comprising a reslstance bridge 414
which is coupled to a pair of skln contact electrodes 416
and 418 forming part of sensor 410. The resistance bridge
414 comprises three resistors, 420, 422 and 424, each
preferably of identical resistance, such as 15 ~ohm. A DC
voltage source 417 is coupled across the junction between
resistor 420 and electrode 416 and the junction between
resistors 422 and 424.
A voltage amplifier 426 is coupled across the
junction between resistor 424 and electrode 418 and the
junction between resistors 420 and 422. The output of the
voltage amplifier is supplied to a comparator 428, which
provides a digital output.
Referring now to Fig. 27B, there is shown
electronic circuitry comprising a capacitance bridge 434
which is coupled to a pair of skin capacitance electrodes
436 and 438, one of which may comprise the hair engage-
ment portion, and another of which may form part of
sensor 410. The capacitance bridge 434 comprises three
capacitors 440, 442 and 444, each preferably of identical
capacitance. An oscillator 447 is coupled across the
junction between capacitor 440 and electrode 436 and the
junction between capacitors 442 and 444.
A voLtage amplifier 446 is coupled across the
junction between capacitor 444 and electrode 438 and the
junction between capacitors 440 and 442. The output of
the voltage amplifier is supplied to a comparator 448,
which provides a digital output.
Reference is now made to Figs. 21A and 21B
which together provide a flow chart illustration of the
operation of control electronics 56 (Fig. 2) in a shaver
employing the sensors of Figs. l9A, 19B and 20. Two modes
of operation are available and controllable by the three
position switch 20 (Fig. lB). If a moustache trimmer mode
W'O g5~33600 , PCT/GB!~ml720
L. 1
J~ _
22
is selected, the cutting beam is not enabled and the
moustache trimmer 18 is operatea.
If a shaver mode of operation is selected, the
input radiation beam 380 is operated initially at low
intensity. The output of sensor 394 (Fig. 19A) indicates
initially whether the beam 380 is properly directed. If
not, the light source 40 ~Fig. 2) is turned off, thus
turning off beam 380. A malfunction warning lndicator 24
(Fig. lA) is illuminated. The operation of the entire
shaver is then disabled until it is reset by service
personnel.
If sensor 394 indicates that the beam 380 is
properly directed, sensor 388 (Fig. lgA~ indicates wheth-
er the cutting region between prism 3B2 and sensor 388 is
clear. If the cutting region is clear, a skin contact
sensor 410 ~Fig. 20) indicates whether the hair engage-
ment portion is in hair cutting engagement with the skin
of the user, If so, shaving operation begins, and beam
380 is provided at high intensity.
I~ the cutting region is not cLear, a malf~nc-
tion warning indicator 26 (Fig. lA) is illuminated. The
user may then clean the cutting area, using a brush or
other suitable implement. If the malfunction warning
indicator is extinguished following cleanlng and the skin
contact sensor 410 indicatlon is received, shaving opera-
tion begins, and beam 380 is provided at high intensity.
If the malfunction warning indicator 26 remains
illuminated after cleaning, another attempt may be made
to clean the cutting area. lf it is successful, and the
indicator 26 is extinguished, and the skin contact
sensor 410 Lndicatlon lS received, shaving operation
begins, as described above.
If the malfunction warning ind'icator 26 remains
illuminated after further cleaning, the receptacle 22 may
be cleaned or replaced. Upon removal of the receptacle
22, the action of microswitch 133 ~Fig. 4A) should cause
~ ss/33600 ~, 9 ~ 7 5 ~ 0l~20
;; ? r ~ ~: ~
. .
23
the shaver to be turned off. If the shaver ls not turned
off due to some malfunction, the cutting beam 380 is
nevertheless immediately turned off. In either event,
following cleaning of the receptacle, the user may turn
the shaver on again and begin the operation anew.
Shaving operation takes place so long as sensor
410 indicates that the hair engagement portion is in hair
cutting engagement with the skin of the user. Upon inter-
ruption of hair cutting engagement with the skin for at
least a predetermined time, such as 100 msec, the cutting
beam is turned off. Followlng turning off of the cutting
beam, and a suitable delay, the beam is operated at low
intensity. Thereafter, the beam is only turned on at high
intensity if positive indications are received from
sensors 388 and 410.
The operation of the shaver has been described
hereinabove for an embodiment according to Fig. l9A. The
operation is similar for the ~ho~ir?nt of Fig. l9E,
wherein the low energy level operation of the light
source is replaced by operation of the auxiliary light
source 400 for determining whether the cutting region is
clear.
According to an alternative embodiment of the
present invention, which is not preferred, the various
sensors may be eliminated. In such a case, the function-
ality described hereinabove with reference to Figs. 21A
and 21B is reduced to a degenerate case.
Reference is now made to Fig. 22, which is a
sectional illustration of part of a shaver housing con-
structed and operative in accordance with a preferred
embodiment of the present invention. Here it is seen that
the hair engagement portion 420 is formed as a relatively
thin insert in a housing 422 and has a non-uniform thick-
ness. In this way, the mechanical strength of hair en-
gagement portion 420 may be maximized, while permitting
the thickness of the hair engagement portion adjacent the
WO 'J~33(~0 ~ PCI/GB95/01220
~ 2~9~751
cuttlng beam 384 to be relatively small. Alternatlvely,
the hair engagement portion 420 may be integrall; formed
with all or part of the housing 422.
Reference is now made to Fig. 23 which is a
simplified illustration indicating typical cross section-
al dimensions of a hair cutting beam 384 (Fig. 19A) used
in the present invention in relation to hairs to be cut
for a laser source. Both for laser and ~irconium, Xenon
or halogen light sources, the width of the beam is great-
er, preferably by a fsctor of at least 2, than its depth
along the axis of hair to be cut.
In Fig. 23 it is seen that preferably, when a
laser is employed, the width of the beam may be approxi-
mately 0.5 mm and its thickness (along the axis of hair
to be cut) may be typically 0.2 mm. The cutting beam
cross section is generally rectangular or elliptic and
indicated by reference numeral 430. One or more hairs,
indicated by reference numeral 432 may lie in the cutting
beam at any time. Any other suitable cutting beam cross
sectional configurations may alternatively be orovided.
It is to be appreciated that althouyh the cutting beam is
shown in Fig. 23 as a perfectly collimated beam, in fact,
it is a focused beam and exhibits divergence which is not
illustrated.
Reference is now made to Pigs. 24A, 24B and
24C, which illustrate various stages in hair cutting in
accordance with one emho~ nt of the present invention.
A consideration of Fiqs. 24A, 24B and 24C shows that
cutting the hair using a laser beam in accordance with
the present invention preferably causes a part 440 of the
hair to be blown away, leaving a part 442 of the hair
attached to the skin and another part 444 of the hair
loose, to be collected in receptacle 22 (Pig. lB).
Re~erence is also made to Figs. 25h and 25B,
which illustrate various stages in hair cutting in ac-
cordance with another embodiment of the present inven-
21 ql 75~
w095J336~ ' PCT/GB95~0122~
tion. ~1ere, the hair is cut into only two pieces. Thisresult may replace that illustrated in Plgs. 24A - 24C
depending on the power of the laser or other light source
employed and depending on the color or other characteris-
tics of the harr to be cut.
It is a particular feature of the present
invention that cutting according to the present inven-
tion, as shown in either Figs. 24A - 24C or Figs. 25A and
25B provides a somewhat rounded and less sharp cut of the
hair attached to the skin, and thus provides a smoother
feel to the user.
The smoothness of the shave, to the extent that
it depends on the configuration of the cut end of the
hair remaining on the user's skin, may be affected by the
nature and the timing of the cutting beam employed. Figs.
26A and 26B are timing diagrams which illustrate two
alternative embodiments of pulsed laser operation partic-
ularly useful in the present invention, which have been
found experimentally to provide satisfactory results in
terms of rounded cutting of hair.
In the ~ho~ r.t of Pig. 26A, a series of
discrete multi-level pulses are employed, each having a
typical duration of lO msec. In the ~mhn~ i ment of Fig.
26B, a continuous varying level pulse is provided, with a
periodicity of approximately 13 msecs. In both cases, the
high power portion of the pulse has a preferred duration
of about 2 msec, the low power portion of the pulse has a
preferred duration of about 8 msecs and the pulses are
preferably separated by about 3 msecs. The preferred
ration of power between the high power portion and the
low power portion is approximately 2 - 3: l.
It is to be appreciated that any suitably
shaped waveform and pulse timing may be employed in
accordance with a preferred ~mho~ir~nt of the invention.
It will be appreciated by persons skilled in
the art that the present invention is not limited by what
WO95/33600 ~ ' ~ PCT/GB95~(11220
~ 1 ~ 1 75 1
26
has been particularly shown and described herelnabove.
The scope of the present invention, as defined by the
claims, is intended to also i~clude equlvalents of the
embodiments described hereinabove.
