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CA 02377053 2001-12-28
67P35CA
Description
Toothbrush
The invention relates to a toothbrush with a toothbrush head supported by a
toothbrush body
according to the preamble of claim 1.
Many types of eccentrically driven toothbrushes with different designs are
commercially available.
Such toothbrushes typically have a toothbrush head that is supported by a
toothbrush body and
interchangeably attached to an electrical hand tool. The toothbrush head has a
bristle carrier
which receives the bristles and is pivotally supported for pivoting about a
pivot axis. The
toothbrush head can be reversibly pivotally driven by an eccentric drive and
pivots alternatingly in
two pivot directions with a specified pivot angle of, for example, 130
degrees.
In a commercially available and widely used toothbrush, the eccentric motion
is produced by an
eccentric gear arranged after the drive motor. The eccentric gear produces a
reversing stroke
motion which is transferred to a drive pin. The drive pin penetrates the
toothbrush body, wherein
the angled end of the drive pin which extends in the axial direction with
respect to the pivot axis of
the bristle carrier, engages in a corresponding bore located on the bristle
carrier. The drive-pin
bore is here radially offset from the pivot axis. In this way, the reversing
stroke action of the lifting
rod is transformed into a reversing pivot motion of the bristle body. Such
eccentric drives for
toothbrushes are described, for example, in the publications U.S. 5,617,601 or
U.S. 5,524,312.
Another variation of an eccentric drive for toothbrushes is described in WO
96137 164. In this
variation, the circular rotary motion of the drive motor is transmitted
directly to a drive shaft which
w penetrates the toothbrush body and has an angled end. The angled end engages
with a
corresponding guide channel located on the bristle carrier, thereby inducing a
reversing pivot
motion in the bristle carrier. This arrangement produces a mechanically very
simple and wear-
.i0 resistant drive. This type of drive also requires very little space, so
that the housing can have a
slim and compact form.
Although a reversibly driven toothbrush of this type operates reliably, it
does have several
disadvantages. In particular, the tooth cleaning ability of such a toothbrush
still needs to be
improved.
It is also known to improve the tooth cleaning ability by superimposing an
additional motion on the
CA 02377053 2001-12-28
z
rotation motion. For example, WO 96/31171 or DE 44 33 914 A1 describe
toothbrushes of this
type with an eccentric drive, wherein the bristle carrier executes a sort of
pivoting motion.
It has been demonstrated, however, that such toothbrush is still unable to
clean teeth optimally.
Moreover, the toothbrush is mechanically complex.
Accordingly, the invention addresses the problem of improving a toothbrush of
the aforedescribed
type in such a way that it has an improved cleaning ability as well as a
simple construction.
The stated problem is solved with a toothbrush of the aforedescribed type by
the characterizing
features of claim 1.
Advantageous embodiments of the invention are described in the characterizing
features of the
1r
dependent claims.
The invention relies on the concept of supporting the bristle carrier for
axial displacement on the
toothbrush head and to drive the bristle carrier with the eccentric drive
reversibly backward and
forward along a linear path. This impresses on the bristle carrier an
oscillating axial displacement
motion which results in an excellent tooth cleaning ability.
According to a first embodiment, the toothbrush head has at least one bearing
channel adapted
to engage with at least one corresponding bearing projection. This embodiment
employs limit
stops that limit the linear travel path of the backward and forward motion
(stroke) of the bristle
carrier.
According to a second embodiment, the axial linear travel can be directly
impressed on the bristle
carrier. For this purpose, a sliding block can be affixed in the axial
direction in the guide channel
of the bristle carrier; alternatively, the sliding block can be moveable in
the axial direction between
limit stops. The sliding block also has a drive-pin bore or a guide channel,
with the eccentric pin
engaging in the guide channel. The bristle carrier is supported on the
toothbrush head for axial
displacement so as to positively follow the corresponding motion of the
eccentric pin in the axial
direction between the two reversing points. Accordingly, as described above,
an axial
displacement motion is superimposed on the rotation motion.
According to additional embodiments, the superimposed axial displacement
motion can also be
produced by providing the bristle carrier with at least one drive-pin channel
which is disposed
along a circumferential segment of the bristle carrier and inclined in the
axial direction. The
CA 02377053 2001-12-28
toothbrush head has a corresponding drive pin adapted to engage with the drive-
pin channel. A
rotary motion is thereby positively transmitted to the bristle body to produce
an axial displacement
motion, since the drive-pin channel has an axial component. This arrangement
provides an
additional simple mechanical link guide proximate to the circumference of the
bristle carrier. It is
sufficient to provide a single drive pin and correspondingly a single drive-
pin channel, wherein the
arrangement of drive pin and drive-pin channel can be interchanged. .
Alternatively, two diametrically opposed drive pins can be arranged on the
toothbrush head. This
arrangement reduces the stress on the drive pins and on the channel, since now
two link guides
produce the axial force.
According to a fifth embodiment, the guide channel can be formed directly in
the bristle carrier.
The eccentric pin directly engages the guide channel and thereby moves
backwards and
forwards between a front and a rear reversing point. A force can thereby be
transmitted via the
sides of the guide channel extending in the axial direction, thereby
reversibly driving the bristle
carrier.
This embodiment operates very quiet due to the small number of moveable parts
and is suited in
particular for high-frequency applications, i.e., so-called fast-running
toothbrushes which are
commonly referred to as "ultrasonic" toothbrushes. The eccentric shaft of such
toothbrushes
rotates with the rotation speed in the range between 15,000 and 25,000
revolutions per minute.
At such high rotation speeds, the components are subjected to particularly
high stress which is
amplified by the continuous reversal of the rotation direction of the
toothbrush body. It is
therefore important to construct the toothbrush in the simplest possible
fashion, as implemented
to a great extent by the aforedescribed measures.
C.
The proposed construction does not require additional constructive measures to
impress on the
bristle carrier the axial displacement motion in addition to the oscillatory
pivoting motion. This
combination results in the excellent tooth cleaning ability mentioned above.
For this purpose, the
length of the guide channel in the axial direction is smaller than the travel
path between the front
and the rear reversing points of the eccentric pin.
The travel of the eccentric pin is bounded by the limited length of the guide
channel in the axial
direction. The bristle carrier is supported for axial displacement on the
toothbrush head so as to
positively execute in the axial direction the corresponding motion of the
eccentric pin between the
two reversing points: This causes an axial displacement motion to be
superimposed on the
rotation motion.
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4
According to a sixth embodiment, a sliding block is affixed in the axial
direction on the bristle
carrier. The sliding block has a guide channel adapted to engage with the
eccentric pin which can
move backward and forward in the axial direction between a front and a rear
reversing point.
According to a seventh embodiment, the sliding block is supported in the guide
channel for axial
displacement. The sliding block has a drive-pin bore adapted to engage with
the eccentric pin.
The eccentric pin thereby guides the sliding block backward and forward
betuveen a front and a
rear reversing points inside the guide channel integrated in the bristle
carrier.
l0
All, embodiments with a sliding block have in common that the sliding block
and the corresponding
recess or guide channel, respectively, disposed on the bristle carrier are
formed so as to enable a
rotation or pivoting motion of the sliding block which opposes the pivot
motion of the bristle body,
so that the eccentric pin engaging with the recess or guide channel is not
subjected to bending
I S stress.
The sliding blocks typically have a cylindrical shape, thereby providing a
reliable support in the
recess and guide channel, respectively. According to a preferred embodiment,
the sliding block
can also have a spherical shape. This embodiment advantageously minimizes the
friction forces
20 produced between the sliding block and the recess or the guide channel,
respectively.
The invention will now be described in more detail with reference to the
embodiments illustrated
in the drawings. It is shown in:
25 Fig. 1 a cross-sectional view of a drive according to a first embodiment;
Fig. 2 an enlarged cross-sectional view (detail) of a drive according to Fig.
1;
Fig. 3 an enlarged cross-sectional view of a drive according to a second
embodiment;
Fig. 4 an enlarged cross-sectional view of a drive according to a third
embodiment;
Fig. 5 an enlarged cross-sectional view of a drive according to a fourth
embodiment; and
Fig. 6 an enlarged cross-sectional view of a drive according to a fifth
embodiment.
The first embodiment of a toothbrush 1 is depicted in Fig. 1.
CA 02377053 2001-12-28
A toothbrush head 12 forms a component of a toothbrush body 10 which can be
interchangeably
connected to a handle portion 60. A bearing journal 16 which engages with a
corresponding
bearing bore 26 of a bristle carrier 20 is disposed on the toothbrush head 12.
The bearing journal
16 therefore represents the rotary/pivot bearing for the bristle carrier 20.
5
The toothbrush head 12 also includes a circumferential bearing channel 14
adapted to engage
with a corresponding bearing projection 24 of the bristle carrier 20. As a
result, the axial travel
path of the bristle carrier 20 with respect to the toothbrush head 12 is
limited, which prevents the
bristle carrier 20 from becoming detached. The bristle carrier 20 includes a
recess 28 extending
in the axial direction, with a sliding block 30 having a guide channel 32
being inserted in the
recess 28. The axial position of the sliding block 30 is defined with respect
to the recess 28 and
the bristle carrier 20, respectively.
;:
An eccentric pin 52 of a drive shaft 50 engages in the guide channel 32, which
in the given
l5 example is in form of a bore. However, the guide channel 32 can also extend
in the axial
direction. The drive shaft 50 is rotatably driven by a motor 40.
Accordingly, the bristle carrier 20 moves in the following fashion:
As seen more particularly from the enlarged diagram X of Fig. 1, the eccentric
pin 52 in the
exemplary cross-sectional view is located at the left reversing point. When
the rotation starts, the
position of the eccentric pin 52 moves to the right, until the eccentric pin
52 reaches a right
reversing point.
The toothbrush head 20 thereby executes the pivoting motion indicated in the
top right corner of
the partial view, namely starting from the left end position indicated by the
solid line to the right,
end position indicated by the dashed line. When the pivoting motion continues,
the eccentric pin
52 returns to its initial position, with the toothbrush body 20 executing a
pivoting motion in the
opposite direction.
The motion can only be performed reliably if the eccentric pin 52 is laterally
guided with a
relatively small clearance, so that the pivotal motion can be transformed
substantially without
play. In addition, the sliding block 30 has to be supported in the recess 28
so as to be able to
pivot about its longitudinal axis in the opposite direction of the rotation of
the bristle carrier 20 to
compensate for the motion of the bristle carrier 20, in order to prevent
bending stress on the
3~ engaging eccentric pin 52. The sliding block 30 and the recess 28 have a
matching circular
cross-section to enable an essentially play-free compensating motion without
noticeable friction.
It should also be noted that the length of the eccentric pin 52 is selected so
that it always
CA 02377053 2001-12-28
6
engages the sliding block 30 regardless of the actual position of the sliding
block 30.
With this simple mechanical arrangement, the continuous rotary motion of the
drive shaft 50 can
be transformed into a reversing rotary motion (pivoting motion).
S
Fig. 2 is an enlarged view of the toothbrush according to Fig. 1. The
following detailed features
can be seen in Fig. 2:
An upper end of a toothbrush body 210 has a toothbrush head 212 with a bearing
journal 216.
I 0 The bearing journal 216 receives a bristle carrier 220 on a bearing bore
226.
The bristle carrier 220 is supported for axial displacement relative to the
toothbrush head 212. A
circumferential bearing projection 224 engages with a bearing channel 214 on
the toothbrush
head 212, wherein the bearing channel 214 is constructed so that the bristle
carrier 220 can
I S travel between a forward axial position, shown in Fig. 2 on the left, and
a rearward axial position,
shown in Fig. 2 on the right. The maximum travel path is referred to as
"stroke."
The bristle carrier 220 includes an axial guide channel 228 in which a sliding
block 230 is
inserted. The sliding block 230 is fixed in the axial direction relative to
the bristle carrier 220. In
20 addition, the sliding block 230 has a drive-pin bore 232 adapted to engage
with an eccentric pin
52 of a drive shaft 50.
Since the eccentric pin 52 is positively coupled with the bristle carrier 220
in the axial direction via
the sliding.block 230, the bristle carrier 220 executes an axial linear motion
which is
25 superimposed on the rotation motion. This high-frequency pulsating motion
in the axial direction
significantly improves the cleaning result. This observation can therefore be
implemented by 1
simple mechanical means, as discussed with reference to the aforedescribed
embodiment.
Fig. 3 shows a toothbrush 300 in which an axial linear motion of a bristle
carrier 320 is also
30 implemented by a positive coupling.
Again, a toothbrush body 310 with a toothbrush head 312 and a bearing journal
316 is provided.
The bearing journal 316 receives the bristle carrier 320 for axial
displacement in a bearing bore
326.
The bristle carrier 320 includes an axial guide channel 328 in which an
axially moveable sliding
block 330 is inserted. The sliding block 330 has a drive-pin bore 332 adapted
to engage with an
CA 02377053 2001-12-28
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eccentric pin 52 of a drive shaft 50.
In addition, two diametrically opposed, radially inwardly-facing drive pins
314 are inserted on the
toothbrush head 312. The drive pins 314 engage with two corresponding drive
channels 324
disposed along a circumferential segment of the bristle carrier 320. The drive
pins 314 are
slightly inclined in the axial direction, so that a rotation motion of the
bristle carrier 320 causes a
positively coupled axial displacement motion.
The toothbrush 400 depicted in Fig. 4 is implemented essentially identical to
the aforedescribed
embodiments.
Again, a toothbrush body 410 has a toothbrush head 412 with a bearing journal
416. The bristle
carrier 420 is supported for longitudinal displacement on the bearing journal
416 by a bearing
bore 426.
The bristle carrier 420 has an axial guide channel 428 in which a sliding
block 430 is supported
for axial displacement. The sliding block 430 has a drive-pin bore 432 adapted
to engage with an
eccentric pin 52 of a drive shaft 50.
So far, this embodiment is identical to the embodiment described with
reference to Fig. 3, except
for the fact that only one drive pin 414 is provided which cooperates with a
drive channel 424.
The axial linear motion is produced by having a drive channel 424 which is
slightly inclined in the
axial direction, thereby defining the axial stroke of the bristle carrier 420.
The only difference between the embodiment of a toothbrush 500 depicted in
Fig. 5 and the
previously described embodiments is that a sliding block 530 has a spherical
shape. The sliding
block 53 has a drive-pin bore 532 adapted to engage with an eccentric pin 52
of a drive shaft 50.
The sliding block is guided for axial displacement in an axial guide channel
528 of a bristle carrier
520. The bristle carrier 520 has a bearing bore 526 which guides the bristle
carrier 520 on a
bearing journal 516 for longitudinal displacement. The bearing journal 516 is
attached to a
toothbrush head 512 of a toothbrush body 510.
A drive pin 514 is disposed on the toothbrush head 512, wherein the drive pin
514 cooperates
with a corresponding drive channel 524 in such a way that a pivoting motion of
the bristle body
520 causes a positively-coupled axial stroke of the bristle body 520.
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The embodiment of the toothbrush 600 illustrated in Fig. 6 is essentially
identical to the
embodiments depicted in Figs. 4 and 5.
Again, a toothbrush body 610 with a toothbrush head 612 is illustrated,
wherein the toothbrush
head 612 has a bearing journal 616. The bristle carrier 620 is supported for
longitudinal
displacement on the bearing journal 616 via a bearing bore 626.
As shown in detail in Figs. 4 and 5, a drive pin 614 cooperates with a drive
channel 624 which is
slightly inclined in the axial direction. This produces the axial stroke of
the bristle carrier 620.
So far, the basic construction of the illustrated embodiment of the toothbrush
is identical to that
described with reference to the embodiments of Figs. 4 and 5, except for the
fact that in the
t' embodiment of a toothbrush 600 depicted in Fig. 6 the guide channel 628 is
formed directly in the
bristle carrier 620.
The eccentric pin 52 which can be set in rotation by the drive shaft 50 which
is in turn driven by a
motor, engages directly with the guide channel 628. The motor drive operating
on the drive shaft
50 causes the eccentric pin 52 to move freely backward and forward in the
guide channel 628
between a front and a rear reversing point. The eccentric pin 52 transmits a
force to the bristle
carrier 620 via the sides of the guide channel 628 which extend in the axial
direction. To
eliminate bending stress in the eccentric pin 52 which engages in the guide
channel 628, the
guide channel 628 has a cavity 634 extending inwardly in the radial direction,
with the cavity 634
receiving the free end of the eccentric pin 52, with a space being formed
between the free end
and the inner wall of the cavity 634.
y_
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List of reference numerals
1 toothbrush
toothbrush body
12 toothbrush head
14 bearing channel
16 bearing journal
bristle carrier
24 bearing projection
10 26 bearing bore
28 recess
sliding block
32 guide channel
motor
15 50 drive shaft
52 eccentric pin
60 handle
200 toothbrush
20 210 toothbrush body
212 toothbrush head
214 bearing channel
216 bearing journal
220 bristle carrier
25 224 bearing projection
226 bearing bore
228 guide channel
230 sliding block
232 drive-pin bore
300 toothbrush
310 toothbrush
body
312 toothbrush
head
314 drive pin
316 bearing journal
320 bristle carrier
324 drive-pin
channel
CA 02377053 2001-12-28
326 bearing bore
328 guide channel
330 sliding block
332 drive-pin bore
5
400 toothbrush
410 toothbrush
body
412 toothbrush
head
414 drive pin
10 416 bearing journal
420 bristle carrier
424 drive-pin
channel
426 bearing bore
428 guide channel
I S 430 sliding block
432 drive-pin
bore
500 toothbrush
510 toothbrush
body
512 toothbrush
head
514 drive pin
516 bearing journal
520 bristle carrier
524 drive-pin
channel
526 bearing bore
c.
528 guide channel
530 sliding block
532 drive-pin
bore
600 toothbrush
610 toothbrush
body
612 toothbrush
head
614 drive pin
616 bearing journal
620 bristle carrier
624 drive-pin
channel
626 bearing bore
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