Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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METHOD, APPARATUS AND SYSTEM FOR ASSESSING HAIR CONDITION
TECHNICAL FIELD
This invention relates to an apparatus, a method and a system for assessing
the condition
of hair, in particular assessing the degree of damage in the hair.
BACKGROUND
In the hair care field it is often important to assess the condition of a
consumer's hair. In
particular it is often valuable to be able to assess the degree of damage
sustained by the hair. It is
known that the surface of a hair fibre becomes rougher when the hair is
subjected to damage, for
instance as a result of brushing, bleaching, perming, colouring, etc. This
reduction in smoothness
is believed to result from changes in the structure of the cuticle, the
outermost part of the hair
fibre.
It is known to assess roughness, and by implication damage by measuring the
degree of
friction generated by subjecting the hair to certain conditions. For instance,
ease of combing is
commonly used as a measure of smoothness. In one combing test the force
required to detangle,
by drawing a comb through, a bundle of hair fibres is used to assess friction,
roughness and
damage.
EP-A-965,834 describes friction-measuring equipment for evaluating the effects
of
cosmetics on skin, hair, membranes and eyes. This equipment assesses friction
by means of
deformation of a deformable assembly on a probe.
JP 63/163143 measures the degree of damage to hair by comparing forward and
reverse
friction forces. These forces are measured by means of a torque meter.
JP 62/273433 measures friction between hairs by passing a fluid in turbulent
flow over a
bundle of hair and measuring friction by detecting pressure loss in the fluid.
It would be desirable to be able to provide systems that allow the convenient
measurement and analysis of surface friction of hair. It would also be
desirable to provide a
means of relating this to levels of damage across a range of hair types:
BRIEF DESCRIPTION OF THE DRAWINGS
The invention will now be illustrated with reference to the Figures, which
show the
following.
Figure 1 is a top cross-sectional view of a preferred device according to the
invention.
Figure 2 is an end view of the same device.
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Figure 3 is a side cross-sectional view of the same device.
Figure 4 is an exploded view of the same device.
Figures 5 to 10 show example traces from six different categories of hair.
DETAILED DESCRIPTION OF THE INVENTION
A method
According to a first aspect of the invention we provide a method for measuring
the
friction generated by a bundle of hair fibres, comprising providing a friction
member, drawing the
friction member through the bundle of hair, whereby a frictional noise signal
is generated, and
capturing the frictional noise signal by a noise sensor. Generally the
captured noise signal is
converted to a form that can be displayed. The converted signal is then
displayed using display
means. Such means may include, but is not limited to display screens selected
from the group
consisting of a computer screen, a cathode ray tube device, and a liquid
crystal display device.
In the invention the friction generated by a bundle of hair is measured. The
hair may be
that of any rnannnal, preferably human, dog, horse, or cat, more preferably
human hair. The
bundle of hair may be a hair sample or switch but is preferably hair growing
on the head of a
consumer.
In the method it is necessary to use both a friction member and a noise
sensor. The
friction member is drawn through the bundle of hair such that it contacts and
passes over the
surfaces of the individual hairs. This creates friction between the friction
member and the hairs.
We find that the frictional noise generated depends upon the level of friction
between the friction
member and the hair surfaces.
The friction member is generally formed from rigid material, preferably
polymeric
material. For instance it may be formed from high-density polyethylene (HDPE).
The friction member is preferably in the form of a comb means having a
plurality,
preferably at least three, and more preferably at least four tines. The comb
means is usually
drawn through the bundle of hair in the manner usual for a comb. This may be
done the subject
whose hair is being assessed or by another.
The frictional noise signal generated is captured by means of a frictional
noise sensor,
preferably a microphone. The microphone may for instance be a standard
electronic microphone
or a noise-cancelling microphone.
Once the frictional noise has been captured it can be displayed and analysed
in any
suitable manner. Preferably a visual display unit is also provided and the
frictional noise sensed
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by the sensor is converted to a signal that is then transferred to the visual
display unit and
displayed. It may for instance be displayed in the form of a trace of sound
amplitude versus time.
This conversion may be achieved using known means.
Preferably the display of the signal is substantially instantaneous, such that
the frictional
noise.being generated by drawing the friction member through the bundle of
hair is displayed at
the same time as the friction member is being drawn through the bundle of
hair.
In the method the frictional noise signal displayed may be obtained from a
single pass of
the friction member through the bundle of hair. Alternatively, the friction
member may be drawn
through the hair two or more times. Results may be accumulated or averaged.
While the inventive method provided herein may adequately be performed alone,
it may
further be performed in combination with other methods for assessing hair
damage. Sttch
additional methods to combined with the method herein may include, but are not
limited to:
intuitive self assessment by the subject, visual or physical assessment by the
subject or another,
such as a beauty counselor, assessment using other devices which measures hair
damage,
chemical assessment of the hair, e.g. assessing the amount of broken versus
unbroken disulfide
bonds of cysteine in a subject's hair, and combinations thereof. Suitable hair
damage measuring
methods for use herein include, but are not limited to methods that employ
devices that assess
roughness, and by implication damage by measuring the degree of friction
generated by
subjecting the hair to certain conditions. For instance, ease of combing is
commonly used as a
measure of smoothness. In one combing test the force required to detangle, by
drawing a comb
through, a bundle of hair fibres is used to assess friction, roughness and
damage.
A Device
The invention also provides, in a second aspect, a device suitable for use in
the method of
the first aspect. The device comprises a comb means having a plurality of
tines and a frictional
noise sensor. The device as a whole is preferably designed so that it is
suitable fox use in the
hand. It is often elongate. The comb means is generally placed at one end of
an elongate device.
Preferably the device is provided in at least two separable parts. In this
case the first part
comprises the comb means and the second part comprises a housing that contains
the frictional
noise sensor and, if required, means for converting the signal detected by the
frictional noise
sensor to a signal transferable to a visual display unit.
The noise sensor should be close to the comb means to achieve optimum
sensitivity to
frictional noise generated. However, generally it should not be in contact
with the comb means.
Thus protection means are generally provided between the noise sensor arid the
comb means to
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prevent contact of the two components. This may be made from any material that
is protective
and acts to prevent contact between the comb means and noise sensor whilst
allowing the passage
of the frictional noise signal generated by contact of the comb means with
hair.
For the purposes of detecting the frictional noise signal generated by comb
means and
hair we find that detection of frequencies in the range from about 50 Hz to
about 5 kHz is
preferred.
A device according the invention is exemplified in Figures 1 to 4. The device
1 is shown
as elongate in shape. It has at its free end 2 a comb means 3 having tines 4.
The comb may be
formed from HDPE. The device 1 may be stored before and in between and after
uses, e.g., on a
magnetic stand.
The passage of the tines through a sample of hair generates frictional noise
that is
detected by the microphone 5. Between the microphone 5 and the comb is
protective means 6
formed from foam, preferably open celled foam. The microphone 5 is connected
to a circuit
board 7, which converts the frictional noise generated to an electrical signal
that passes along the
cable 8 to means (not shown) for converting the signal into a visual display.
For ease of use, the
cable 8 may be situated as retractable.
The device 1 is constructed such that the microphone 5 detects signals at all
times. The
switch 9 can be switched by pressing the switch cover 10 to indicate that
display and/or recording
of the frictional noise signal should occur. The recording is indicated by an
"on/off' LED, whose
signal is visible from the exterior by means of the light pipe 12.
The microphone and circuit board are contained in a protective housing 13 that
is
removeably connected with the comb 3. The comb 3 may be removed for instance
by twisting.
This has the advantage that the comb may be removed for cleaning and replaced
with a new
comb.
Although it is known that there is a relationship between friction generated
by combing
hair and damage to that hair we have found that this is not the only
significant factor when
frictional noise is, as in the invention, used to assess friction levels.
Frictional noise generation
gives an accurate indication of friction levels but we have found that it is
important to determine
A
the characteristics of the hair being tested in order to assess whether the
increased friction is due
to damage and/or a rough hair surface or to other factors (for example hair
curliness). We have
found that this allows any particular hair sample (e.g. the hair of an
individual consumer) to be
analysed accurately for the level of damage in that particular hair sample. In
the invention,
varying friction and damage levels within a single sample may be observed by
means of changes
in amplitude as the comb means is passed through the sample.
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A System
Thus according to a third aspect of the invention we provide a system for
assessing the
level of damage in a test sample of hair, comprising
defining a predetermined number of hair categories H,
associating with each hair category H a standard trace T representative of the
frictional
noise signal generated when a standard sample in that hair category is
subjected to the method
described above,
assigning the test hair sample to one of the predetermined categories Ht,
carrying out the method described above on the sample of hair,
visually displaying the frictional noise signal generated as a trace on a
screen,
and comparing the sample's trace Tt with the standard trace T associated with
the
category Ht.
In this system it is necessary to define a number of predetermined categories
of hair.
These categories are defined by their tendency to give friction. For instance,
in one system, three
categories: high friction, moderate friction and low friction could be
predetermined.
Hair of various types is then assigned to one of these predetermined
categories according
to relevant factors. These factors may be selected from ethnic origin (for
instance if the hair is of
European, Asian or African origin); waviness (whether the hair is straight,
wavy or curly);
whether the hair has been previously subjected to treatments (perming,
bleaching or colouring).
Thus this aspect of the invention is based at least in part on the realisation
that frictional noise
levels depend not only upon damage levels but on other hair characteristics.
With each category is associated a standard trace. This trace is an
illustration of the
frictional noise expected to be generated by a sample of hair in the defined
category when
subjected to the method described above.
In the system of the invention the hair sample to be tested, which may be a
hair switch but
is generally hair growing on the head of a consumer, is assigned to one of the
predefined
categories according to the factors discussed above.
The process of the invention is then carried out on the sample to be tested,
generally in
substantially the same manner as carried out to generate the standard traces
above. The frictional
noise signal generated is displayed as a trace on a screen and this sample
trace is compared with
the standard trace. It can then be assessed whether the hair sample is more or
less damaged than
would be expected from the characteristics above.
A significant factor is the amplitude of the frictional noise generated. In
particular, when
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the trace is presented as a graph of the relationship between amplitude and
time then the area
under the curve is generally proportional to the level of friction.
Thus this system has the advantage that the level of damage in any particular
hair sample
can be accurately assessed whilst taking into account the level of friction to
be expected as a result
of its characteristics. For instance, virgin (untreated) straight hair
naturally gives a lower level of
frictional noise than virgin curly hair. Thus in order to assess the necessity
for use of treatment
products on the hair it is important to predetermine the natural level of
frictional noise which
would be expected for hair of the relevant category.
For example, the hair categories illustrated in Figures S to 10 may be used as
the
predefined categories and the traces used as the standard traces in a method
according to the
invention. Figure 5 shows a standard trace for grey permed European hair.
Figure 6 shows a
standard trace for brown curly European hair. Figure 7 shows a standard trace
for brown Asian
hair. Figure ~ shows a standard trace for grey hair. Figure 9 shows a standard
trace for brown
permed and bleached European hair. Figure 10 shows a standard trace for brown
virgin European
hair. The level of friction decreases from Figure 5 to Figure 10. This is
proportional to the area
under the trace and, generally, the amplitude of the trace.
The system can be used by the consumer directly but is preferably applied by
an operative
or adviser, for instance in a store or salon. It is contemplated that after
the assessment has been
made appropriate treatment for the hair may further be proposed.
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