U.S. patent application number 10/518838 was filed with the patent office on 2005-09-22 for wear-indicating filament.
This patent application is currently assigned to Koninklijke Philips Electronics N.V.. Invention is credited to Mikula, Christian.
Application Number | 20050204500 10/518838 |
Document ID | / |
Family ID | 29797245 |
Filed Date | 2005-09-22 |
United States Patent
Application |
20050204500 |
Kind Code |
A1 |
Mikula, Christian |
September 22, 2005 |
Wear-indicating filament
Abstract
The invention relates to a wear-indicating filament for use in a
brush, comprising a central axis, a core extending along the
central axis, said core being covered by a layer having a
pre-determined resistance to wear, said layer wearing away over a
pre-determined period of use dependent on its resistance to wear
and exposing at least a part of the core after said period. The
layer comprises a material which absorbs relatively little water
and the core comprises, seen in a cross-section, at least two
segments in an asymmetrical arrangement along the central axis of
the filament, which segments have a mutually different absorption
of water and show a difference in expansion when the layer has worn
away and the core is exposed to water. When the at least two
segments of the cross-section of the filament become exposed to
water, the segments show a difference in absorption of water and a
difference in expansion resulting from this absorption. The
difference in expansion causes the filament to bend, which will be
noticed by the user visually and during use of the brush on the
teeth. This provides a clear indication that the brush should be
replaced, because the bent filament give a warning to the user in a
visual manner and in a tactile manner.
Inventors: |
Mikula, Christian;
(Wernberg, AT) |
Correspondence
Address: |
PHILIPS INTELLECTUAL PROPERTY & STANDARDS
P.O. BOX 3001
BRIARCLIFF MANOR
NY
10510
US
|
Assignee: |
Koninklijke Philips Electronics
N.V.
Groenewoudseweg 1
BA Eindhoven
NL
5621
|
Family ID: |
29797245 |
Appl. No.: |
10/518838 |
Filed: |
December 21, 2004 |
PCT Filed: |
June 4, 2003 |
PCT NO: |
PCT/IB03/02484 |
Current U.S.
Class: |
15/207.2 |
Current CPC
Class: |
A46B 15/001 20130101;
A46B 2200/1066 20130101; A46B 15/0002 20130101; A46D 1/00
20130101 |
Class at
Publication: |
015/207.2 |
International
Class: |
A46B 015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2002 |
EP |
02077584.7 |
Claims
1. A wear-indicating filament for use in a brush, comprising: a
central axis; a core extending along the central axis; said core
being covered by a layer having a pre-determined resistance to
wear; said layer wearing away over a pre-determined period of use
dependent on its resistance to wear and exposing at least a part of
the core after said period, characterized in that the layer
comprises a material which absorbs relatively little water and the
core comprises, seen in a cross-section, at least two segments in
an asymmetrical arrangement along the central axis of the filament,
which segments have a mutually different absorption of water and
show a difference in expansion when the layer has worn away and the
core is exposed to water.
2. A wear-indicating filament as claimed in claim 1, characterized
in that a first segment comprises a polyamide chosen from a group
comprising PA-6, PA-6.6.
3. A wear-indicating filament as claimed in claim 1, characterized
in that a second segment comprises a polyamide chosen from a group
comprising PA-6.10, PA-6.11, PA-6.12.
4. A wear-indicating filament as claimed in claim 1, characterized
in that the layer comprises a material chosen from a group of
polyester, polyethylene and polypropylene.
5. A wear-indicating filament as claimed in claim 1, characterized
in that the layer is formed by two layer parts on an outer surface
of the core having mutually differing wear resistances, and the
core comprises a first and a second segment of the same material,
which segments have a mutually different absorption of water and
show a difference in expansion when a layer part has worn away and
the core is exposed to water.
6. A wear-indicating filament as claimed in claim 1, characterized
in that the layer and at least one of the segments have mutually
different colors.
7. A brush comprising a plurality of wear-indicating filaments,
comprising: a longitudinally extending core of a first material;
said core being covered by a layer of a second material having a
predetermined resistance to wear; said layer wearing off from the
core over a pre-determined period of use dependent on the
resistance to wear and exposing at least a part of the core after
said period, characterized in that the wear-indicating filaments
comprise filaments according to any of the preceding claims.
8. A brush as claimed in claim 9, characterized in that said brush
comprises a brush for a personal care appliance chosen from a group
of toothbrushes and cosmetic brushes, or a brush chosen from a
group of floor care brushes, paint brushes, and industrial brushes.
Description
[0001] The invention relates to a wear-indicating filament for use
in a brush, comprising a central axis, a core extending along the
central axis, said core being covered by a layer having a
pre-determined resistance to wear, said layer wearing away over a
pre-determined period of use dependent on its resistance to wear
and exposing at least a part of the core after said period.
[0002] The invention further relates to a brush comprising a
plurality of wear-indicating filaments each comprising a central
axis, a core extending along the central axis, said core being
covered by a layer having a predetermined resistance to wear, said
layer wearing away over a pre-determined period of use dependent on
its resistance to wear and exposing at least a part of the core
after said period.
[0003] A filament of the type defined in the opening paragraph is
known from GB 2323026. The known filament is comprised in the brush
of a toothbrush and comprises a core made of a material of one
color, covered by a layer of a biodegradable polymer material of
another color. The core is made of a polyamide type which absorbs
relatively little water when the material is in contact with water.
When the filaments are used with a cleaning agent such as
toothpaste, the layer disintegrates and mechanically wears off over
a controlled period of time, exposing the core of a different
color. The exposure of the core is an indication for the user that
the brush has to be replaced by a new one.
[0004] A disadvantage of the known filament is that the user may
continue to use the brush after the indication to replace the brush
by exposure of the core. In this manner the user is using a brush
which is becoming more and more soiled with bacteria and remainders
over time, which exposes the user to a hygienic risk.
[0005] It is an object of the invention to provide a
wear-indicating filament for use in a brush which gives a clear
indication that the brush should be replaced and which reduces the
risk of the user continuing to use the brush after this indication
has been given.
[0006] To achieve this object, a wear-indicating element according
to the invention is characterized in that the layer comprises a
material which absorbs relatively little water and the core
comprises, seen in a cross-section, at least two segments in an
asymmetrical arrangement along the central axis of the filament,
which segments have a mutually different absorption of water and
show a difference in expansion when the layer has worn and the core
is exposed to water. The layer which covers the core absorbs almost
no water during use and thus ensures proper functioning of the
brush. After a certain period of use this layer is worn away, which
causes the core to be exposed to water during use. When the at
least two segments of the cross-section of the filament become
exposed to water, the segments show a difference in absorption of
water and a difference in expansion resulting from this absorption.
The difference in absorption may be the speed with which water is
absorbed or the amount to which it is absorbed. The difference in
expansion causes the filament to bend away laterally from its
central axis, which will be seen by the user and felt during use of
the brush on the teeth. This provides a clear indication that the
brush should be replaced, because the bent filaments give a warning
to the user in a visual manner and in a tactile manner.
[0007] It is advantageous when a first segment comprises a
polyamide chosen from a group comprising PA-6, PA-6.6. These
materials are suitable for forming one of the segments within the
core, because PA-6 has a relatively high maximum water absorption
of 10%, and PA-6.6 of 8.5%, and both materials expand relatively
quickly when they are exposed to water.
[0008] It is advantageous when a second segment comprises a
polyamide chosen from a group comprising PA-6.10, PA-6.11, PA-6.12.
These polyamides have a relatively low water absorption and are
less strongly affected when they are exposed to water compared with
the PA-group described above. The combination of these two types of
material in the core provides an advantageous embodiment of the
segments which have a mutually different absorption of water and
show a difference in expansion when the layer has worn away and the
core is exposed to water.
[0009] It is advantageous when the layer comprises a material
chosen from a group comprising polyester, polyethylene,
polypropylene. These materials absorb practically no water, which
makes them suitable for forming the layer which covers the core and
which wears during use. These materials thus prevent the segments
within the core from coming into contact with water during the
pre-determined period of use of the filament and ensure a proper
functioning of the filament in the brush during this period.
[0010] An embodiment of a filament according to the invention is
characterized in that the layer is formed by two layer parts on an
outer surface of the core having mutually differing wear
resistances, and the core comprises a first and a second segment of
the same material which have a mutually different absorption of
water and show a difference in expansion when a layer part has worn
away and the core is exposed to water. After a certain period of
use the first layer part with the lowest resistance to wear will
wear first, while the other layer part stays intact. In this manner
the layer is worn in an asymmetrical manner along the central axis.
A first segment in the core which is present near the first layer
part comes into contact with the water first and absorbs the water,
which causes this segment to expand. The other segment has not yet
been exposed to any water, which causes a difference in expansion
between the two segments, which makes the filament bend.
[0011] An embodiment of a filament according to the invention is
characterized in that the layer and at least one of the segments
have mutually different colors. This further enhances the visual
indication to the user that the brush should be replaced.
[0012] According to the invention, a brush of the type as defined
in the opening paragraph is characterized in that the
wear-indicating filaments comprise filaments according to the
invention. In further embodiments of a brush according to the
invention, the brush comprises a brush for a personal care
appliance chosen from a group of toothbrushes and cosmetic brushes,
or a brush chosen from a group of floor care brushes, paint
brushes, and industrial brushes. The wear-indicating filaments
according to the invention can be advantageously applied in various
kinds of brushes.
[0013] The invention will be described in more detail hereinafter
with reference to the drawings, in which:
[0014] FIG. 1 is a side elevation of a brush with filaments
according to a first embodiment of the invention;
[0015] FIG. 2 shows a cross-section of a filament taken on the line
II-II in FIG. 1;
[0016] FIG. 3 shows the filament according to the invention in a
bent state;
[0017] FIG. 4 shows a cross-section of a second embodiment of a
filament according to the invention; and
[0018] FIG. 5 shows a cross-section of a third embodiment of a
filament according to the invention.
[0019] FIG. 1 shows a brush 1 comprising a plurality of
wear-indicating filaments 2 according to the invention. Each
filament 2 comprises a core 3 which extends along a central axis 5
and which is covered by a layer 4 which has a predetermined
resistance to wear. Said layer 4 wears away over a pre-determined
period of use dependent on the resistance to wear, and after said
period at least a part of the core 3 is exposed. The layer 4
comprises a material which absorbs relatively little water and the
core 3 comprises, seen in a cross-section A along the line II-II in
FIG. 1, at least two segments 31, 32 in an asymmetrical arrangement
along the central axis 5 of the filament 2, as can be seen in FIG.
2. The segments 31, 32 have a mutually different absorption of
water and show a difference in expansion when the layer 4 has worn
away and the core 3 is exposed to water. Because of the difference
in expansion between the segments 31 and 32, the filament 2 bends
as shown in FIG. 3. The bent filaments in the brush 1 are a clear
indication for the user that the brush has to be replaced for a new
one.
[0020] In this embodiment, the first segment 31 comprises a
polyamide of type PA-6, and the second segment 32 comprises a
polyamide of type PA-6.12. PA-6 has a relatively high maximum water
absorption of 10% and expands relatively quickly when exposed to
water. This material may thus be advantageously used for the first
segment in a filament according to the invention. PA-6.12 has a
relatively low water absorption and expands less and more slowly
when exposed to water compared with the PA-6 type polyamide
described above. The combination of these two types of polyamide
material in the core provides an advantageous embodiment of the
segments. It is noted that other combinations of polyamide or
different materials may be used for the segments, as long as the
segments 31, 32 are made of materials having a mutually different
absorption of water and showing a difference in expansion when the
layer 4 has worn away and the core 3 is exposed to water. For
example, the segments may alternatively comprise PA-6.6 and PA-6.10
respectively.
[0021] In this embodiment, the layer comprises polyester. It is
noted that the layer may alternatively comprise polyethylene or
polypropylene, or any other known material, as long as it is
comprises a material which absorbs relatively little water. One of
the segments may, for example, be made from the same material as
the layer.
[0022] FIG. 4 shows a cross-section of a second embodiment of a
filament 2' according to the invention, in which the core 3'
comprises, seen in a cross-section, three segments 31', 32', 33' in
an asymmetrical arrangement along the central axis of the filament,
which have a mutually different absorption of water and show a
difference in expansion when the layer has worn away and the core
is exposed to water. These segments may alternatively comprise
combinations of polyamide or other materials, as long as the
segments 31', 32', 33' are made of materials having a mutually
different absorption of water and showing a difference in expansion
when the layer 4' has worn away and the core 3' is exposed to
water. It is noted that also more than three segments may be
comprised in the core of a filament according to the invention. In
this embodiment, the layer 4' and the segment 31' have mutually
different colors. The wearing of the filament is further supported
visually by the fading color of the layer 4', and the color of the
first segment 31' becoming visible through the worn layer. When the
layer has worn away completely and the first segment 31' is
visible, this provides an additional indication that the brush
should be replaced, next to the bending of the filament caused by
the segment materials having a mutually different absorption of
water and showing a difference in expansion when the layer 4' has
worn away and the core 3' is exposed to water.
[0023] FIG. 5 shows a cross-section of a third embodiment of a
filament 2" according to the invention, in which the layer 4" is
formed by two layer parts 41, 42 on an outer surface 43 of the core
3" having mutually differing wear resistances, and the core 3"
comprises a first and a second segment 31", 32" of the same
material, which segments have a mutually different absorption of
water and show a difference in expansion when a layer part 41 has
worn away and the core is exposed to water. In this embodiment, the
first layer part 41 has the lowest resistance to wear, which
resistance is chosen so as to expire at the end of the period in
which the brush can be used without hygienic risk. When this
preferred period of use has ended, the first layer part 41 has worn
away and the first segment 31" of the core 3", which is present
directly beneath the first layer part 41, gets exposed to water.
This segment 31" absorbs the water more quickly and thus expands
more quickly than the second segment 32", which causes the filament
2" to bend.
[0024] It is observed that the brush 1 may be a brush for a
personal care appliance such as an electrical toothbrush, or a
facial cleaning device. The brush may alternatively be a brush
chosen from a group of floor care brushes, paintbrushes, and
industrial brushes.
* * * * *