Note: Descriptions are shown in the official language in which they were submitted.
1091436
The invention relates to a hair-trimming appa-
ratus comprising a comb-like stationary cutting element
; and a comb-like cutting element which is drivable rela-
tive thereto, each cutting element having a row of
teeth each of which projects from the cutting element
in a direction extending transversely of the direction
in which the row of teeth extends, and each of which has
a cutting edge which is arranged for cooperation with a
cutting edge of a tooth of the other cutting element.
Such a hair-trimming apparatus is known from,
for example, our prior United Kingdom Specification
No. 1,507,196.
It has been found that practically all hairs
which enter the spacer between adjacent pairs of cooperat-
ing teeth of the known apparatus are cut off immediately.
It is an object of the invention to provide a
hair-trimming apparatus whose teeth can penetrate the
hair without all the hairs which enter the spaces be-
tween adjacent pairs of cooperating teeth being cut.
In particular, a hair-trimming apparatus is aimed at
which permits hairs below the surface to be cut whilst
hairs at the surface are left uncut, so that the appa-
ratus is very suitable for thinning hair.
According to the invention there is provided
a hair-trimming apparatus comprising a comb-like sta-
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lG91436
tionary cutting element and a comb-like cutting element which is drivable
relative thereto, each cutting element having a row of teeth each of
which pro~ects from the cutting element in a direction extending trans-
versely of the direction in which the row of teeth extends, and each of
which has a cutting edge which is arranged for cooperation with a cutting
edge of a tooth of the other cutting element, characterized in that the
movement of the drivable cutting element takes place at least partly in
a direction which extends transversely of the direction in which the row
of teeth of said cutting element extends.
A side edge of a tooth is one that extends transversely of
the direction in which the respective row of teeth extends.
This construction ensures that during cutting the apparatus
also has a certain combing action, so that the teeth can readily penetrate
in the hair, and that only hairs which enter the paths of the re-entrant
edge portions of the teeth are cut.
According to one embodiment of the hair-trimming apparatus
in accordance with the invention, the movement of the drivable cutting
element takes place at least partly in a direction which extends trans-
versely of the direction in which the row of teeth of said cutting element
extends. As a result of this, the spaces between adjacent pairs of
cooperating teeth remain fairly large.
Preferably, the drivable cutting element is reciprocable in
a direction parallel to that in which the teeth of said element project
from the element, and the two teeth of each pair of cooperating teeth
' substantially coincide. This gives optimum spacing between ad~acent
pairs of teeth, which is very favourable for the combing action.
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Preferably, one or each side edge of each tooth of the station-
ary cutting element has a re-entrant portion which constitutes a cutting edge.
A preferred embodiment of the hair-trimming apparatus in accord-
ance with the invention is characterized in that the cutting edge or each
cutting edge of each tooth of the stationary cutting element extends trans-
versely of the direction in which the tooth projects from the cutting element,
and that the cutting edge or each cutting edges of each tooth of the drivable
cutting element is situated at the distal end of the tooth and also extends
transversely to the direction in which the tooth projects from the cutting
element.
The distance between the cutting edges of the two teeth of a pair
of cooperating teeth in any given position of the drivable cutting element
relative to the stationary cutting element, and measured in the direction in
which the teeth project from the cutting elements, differs from the distance
between the cutting edges of the two teeth of another pair of cooperating
teeth. This reduces the number of hairs that are cut simultaneously at any
given instant and thus reduces the peak load on the driving motor.
Still another embodiment of the hair-trimming apparatus in accord-
ance with the invention is characterized in that each cutting element is pro-
vided with two rows of teeth, a first row of teeth of which the teeth extendin a direction which is substantial parallel to the direction in which the
drivable element is reciprocable and a second row of teeth of which the teeth
extend in a direction substantial perpendicular to the direction in which the
drivable element is reciprocable.
Embodiments of the invention will now be described in more detail
with reference to the accompanying drawings, in which
Figure l is a perspective view of the front most part of a hair-
trimming apparatus according to an embodiment of the invention,
Figure 2 shows an exploded perspective view of the hair-trimming
apparatus of Figure 1,
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Figure 3 shows some pairs of cooperating tee~h of the hair-
trimming apparatus of Figure 1 on an enlarged scale,
Figure 4 is a cross-section taken on the line IV - IV of
Figure 3,
Figures 5a, b, c, d, e, f, g and h show other examples of pairs
of cooperating teeth,
Figure 6a shows schematically the cutting elements of a hair-
trimming apparatus according to another embodiment of the invention in which
the drivable cutting element performs a rotary movement,
Figures 6b and 6c are diagrammatic sectional views of the cutting
elements of Figure 6a taken at right angles to one another,
Figure 6d is an enlarged view of parts of two cooperating teeth
of the cutting elements of Figure 6a, and
Figure 7 shows parts of the cutting elements of a hair-trimming
apparatus according to a further embodiment of the invention in which the dis-
tance between the cutting edges of the two t0eth of each pair of cooperating
teeth in any given position of the drivable element is different from this
distance in the other pairs of teeth.
Figure 8 shows in a similar way as Figure 2 a hair-trimming appar-
atus according to another embodiment of the invention in which each cuttingelement is provided with two rows of teeth.
The hair-trimming apparatus shown in Figure 1 comprises a housing
1 which consists of two halves 2 and 3. The housing accommodates an electric
drive motor, not shown. The hair-trimming apparatus further comprises a
stationary comb-like cutting element 4 and a comb-like cutting element 5
which cooperates therewith and is drivable by the motor. The cutting elements
are each provided with a row of teeth 6 and 7 respectively and are together
disposed near an end of the housing in such a way that the rows of teeth pro-
ject from the housing. Resilient means for resiliently urging the cutting
elements 4 and 5 against each other are constituted by four leaf springs 8
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which form part of a single component 9. The part of the cutting elements
4, 5 situated inside the housing 1 is covered by a flap 10 which is hingedly
connected to the housing section 2.
As is shown in Figure 2, the stationary cutting element 4 is lo-
cated by projections 12 on the housing section 3, the cutting element 4 hav-
ing apertures 11 which fit over the projection 12. At the front this cutting
element bears on a rim 13 of the housing section 3. The drivable cutting
element 5 is movable relative to the stationary cutting element 4 in the tooth
direction, i.e. the direction, designated by arrow P, in which the teeth 6
and 7 project from the cutting elements. The cutting element 5 is guided in
this movement by the projections 12, which engage with a sliding fit in apert-
ures 14 in the cutting element 5, the dimensions of the apertures 14 in the
tooth direction P being slightly greater than those of the projections 12.
Furthermore the two cutting elements are provided with supporting surfaces 15
and 16. The cutting elements are in sliding contact with each other at the
teeth 6, 7 and at the supporting surfaces 15, 16. The drivahle cutting ele-
ment 5 is driven through a drive lever 17 so as to reciprocate in a direction
parallel to the tooth direction P. The drive lever itself is oscillated by
the motor in a direction transverse to the tooth direction P. As the de-
sired movement of the cutting element 5 is substantially perpendicular to the
~ movement of the drive lever 17, the cutting element 5 is provided with a slot
; 19 which extends obliquely of the tooth direction P and in which a pin 18 of
the drive lever engages with a sliding fit.
Figures 3 and 4 show the teeth 6 and 7 respectively on an enlargedscale. In the two side edges of each of the teeth 6 of the stationary cutt-
ing element 4 triangular recesses 20 are formed. Each side edge of each
tooth 6 thus has a re-entrant portion 21 which forms part of the boundary of
the recess 20, and this re-entrant portion constitutes a cutting edge of the
tooth. In the embodiments shown in Figures 3 and 4, each cutting edge 21 is
perpendicular to the tooth direction P. Each of the teeth 7 of the drivable
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cutting element 5 has a cutting edge 22 on its distal end for cooperation with
the two cutting edges 21 of a tooth 6 of the stationary cutting element 4.
The cutting edges 22 also are perpendicular to the tooth direction P. In the
present example the two teeth of each pair of cooperating teeth 6 and 7 coin-
cide. During the movement of the cutting element 5 the distance between
every adjacent pairs of cooperating teeth remains constant, so that the space
between the two pairs of teeth remains sufficiently large to ensure a satis-
factory combing action, which is necessary for the penetration of the hair
with the toothed cutting elements. In operation the cutting elements have a
thinning action on the hair due to the fact that during the reciprocating
movements of the cutting element 5 between the position shown in full times
in Figure 3 and the position indicated by the broken lines 23, which repre-
sent the distal ends of the teeth 7 in the latter position, only those hairs
are cut which are caught in the recesses 20. In general this will only be a
fraction of the total number of hairs that enter the spaces between the pairs
of teeth.
The re-entrant edge portions of the teeth which constitute the
cutting edges thereof may be obtained in ways other than by forming triangu-
lar recesses, or indeed recesses of any shape, in the side edges of the teeth.
Also, the mode of movement of the drivable cutting element may be other than
a pure reciprocation in the tooth direction P.
For a hair-thinning apparatus it is important that in every posi-
tion of the cutting elements relative to each other, spaces of sufficient
width are left between adjacent pairs of teeth to allow the pairs to enter
these spaces, i.e. there should continually be a combing action. Figures 5a,
b, c, d, e, f, g and h show a variety of alternative constructions for the
pairs of cooperating teeth, an arrow indicating the direction of movement
of the drivable cutting element in each case. The cutting edges bear the
same reference numerals as in Figure 3.
Figure 5a shows a pair of cooperating teeth 6 and 7 in which each
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side edge of the stationary tooth 6 has a re-entrant portion 21 which extends
obliquely of the tooth direction P to form an oblique cutting edge. The re-
entrant portions are formed by cutting oblique slots in the side edges of the
tooth 6. The movable tooth 7, which in this embodiment again reciprocates
in a direction parallel to the tooth direction P, has two oblique cutting
edges 22 on its distal end for cooperation one with each of the two cutting
edges 21 of the stationary tooth 6, the angle and direction of the obliquity
of each cutting edge 22 being the same as those of the corresponding cutting
edge 21.
Figure 5_ shows a construction similar to that shown in Figure Sa
except that the tooth 7 is movable in a direction transversely to the tooth
direction P. The arrows indicate two alternative modes of reciprocable move-
ment.
Figure 5c shows a construction in which the stationary tooth 6 of
a pair of cooperating teeth 6 and 7 has a cutting edge on only one side of
the tooth, the cutting edge being formed by a re-entrant portion 21 of the
~` side edge of the tooth, which portion extends at right angles to the tooth
direction P and is formed by a reduction in the width of the tooth. The mov-
able tooth 7 has a cutting edge 22 on its distal end for cooperation with the
cutting edge 21 of the stationary tooth 6, and in this embodiment performs a
rotary movement in operation, as indicated by the broken-line arrow. The
cutting edge 22 also extends at right angles to the tooth direction P.
Figure Sd shows a construction similar to that shown in Figure 5c
except that the movable tooth 7 has a reciprocatory instead of a rotary action.
Figure 5e shows a construction in which the stationary tooth 6
and the movable tooth 7 have a cutting edge on only one side of the tooth.
The arrows indicate two possible modes of reciprocable movement.
Figure 5f shows a pair of cooperating teeth 6 and 7 in which one
side edge of each tooth has a re-entrant portion 21 and 22 respectively con-
stituting a cutting edge. The re-entrant portion 21 is formed by part of the
1091436
boundary of a recess in the side edge of the tooth 6 and the re-entrant por-
tion 22 is formed by a reduction in the width of the tooth 7. The movable
tooth 7 reciprocates in a direction parallel to the tooth direction P, and
the two cutting edges 21 and 22 extend obliquely of this direction.
Figure 5g shows a construction in which each tooth of a pair of
cooperating teeth 6 and 7 has two cutting edges on each side of the tooth.
The cutting edges 21 of the stationary tooth 6, which edges are formed by re-
entrant portions 21 of the side edges of the tooth, extend obliquely of the
tooth direction P, and the cutting edges 22 of the movable tooth 7 extend at
right angles to this dlrection. The tooth 7 reciprocates in a direction par-
allel to the tooth direction P.
In the construction shown in Figure5 , each tooth of a pair of
cooperating teeth 6 and 7 again has two cutting edges on each side of the
' tooth, as in Figure 5g, but all the cutting edges extend at right angles to
,~ the tooth direction P. The movable tooth 7 again reciprocates in a direction
parallel to the tooth direction P.
Figures 6a, b, c show a construction in which the drivable cut-
ting element 24 performs a rotary movement. The cutting element 24 is driven
through two synchronously rotating eccentric pins 25 and 26 formed on the
` ~20 ends of spindles 27 and 28. These spindles, which pass through openings in
the stationary cutting element 29, are driven through two sets of bevel gears
30 and 31 by a motor spindle 32. Figure 6d shows the path of movement of a
point A on a tooth 33 of the drivable cutting element. The reference numeral
34 refers to a cooperating tooth of the stationary cutting element. The con-
struction of these teeth is similar to the construction shown in Figure 5c.
If hairs are being cut by a plurality of pairs of teeth at the
same instant, this presents a high peak load to the motor, and the power of
the motor should be adapted thereto. This high peak load can be avoided or
reduced by the use of a construction in which the distance between the cutt-
- 30 ing edges of the two teeth of a pair of cooperating teeth in any given position
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1(~91436
of the drivable cutting element relative to the stationary cutting element,
and measured in the tooth direction P, differs for a number of pairs of teeth.
Figure 7 shows an example of this. The distance a between cutting edges 35
and 36 of the teeth 6 and 7 respectively of each pair of cooperating teeth is
greater than the corresponding distance in the adjacent pair of teeth on the
side nearer the centre of the rows of teeth (al ~ a2 ~ ......
C a5 ~ ......... ). For this purpose the cutting edges 35 are staggered along
the row of the teeth 6 from the centre of the row to the ends thereof so that
they are situated progressively nearer *he distal ends 37 of the teeth. It
is alternatively possible to stagger the cutting edges 36.
:: I
The exploded perspective view of Figure 8 shows a hair-trimming
apparatus of which each cutting element 4, 5 is provided with two rows of
teeth. At the sides 42 and 43 respectively the cutting elements are provided
with first rows of teeth 6 and 7 as described in connection with the embodi-
ment of Figures 1 and 2. These teeth 6 and 7 project from the cutting ele-
ments 4 and 5 respectively in a direction which is substantial parallel to
I the direction of movement of the movable cutting element 4.
;l At the sides 38 and 39 of the cutting elements 4 and 5 the second
rows of teeth 40 and 41 respectively are located. These teeth 40 and 41 pro-
ject in a direction which is substantial perpendicular to the direction of
movement of the movable cutting element 4.
When the movable cutting element is driven the rows of teeth 40
and 41 act as the teeth of a conventional trimmer so that in this way the
apparatus can be used for both a thinning and trimming performance.
Obviously, the hair-trimming apparatus may be constructed as
part of another type of personal-care appliance, such as a shaving apparatus
or massage apparatus.
