Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02616546 2007-12-28
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Description
ROTATABLE ARMREST
Field Of Invention
This invention relates to rotatable armrests and particularly relates to an
armrest for a chair
having a first member connected to the chair, a second member selectively
rotatable relative
to the first member and structure disposed between the first and second
members for resisting
the rotational movement between the first and second members. A method of
resisting the
rotational movement of an armrest is also shown.
Background to the Invention
A pair of armrests are often associated with chairs to provide support for a
users forearms
while working despite the differences in sizes, shapes and preferences of
users. This is
particularly important for individuals having desk jobs where persons may stay
seated for
long periods of time and where different users use the same chair. It is also
important for
users that are different in size to be able to adjust the armrests to a
lateral position that is
comfortable for them. In this regard it is common for armrests to be
selectively rotatable
about a vertical axis.
For example, U.S. Patent No. 5,769,496 relates to an adjustable arm apparatus
including a
lateral shaft having a stop member, an armrest frame rotatably mounted on the
shaft allowing
limited rotation and an actuator to act on the stop member to adjust the
positioning and
degree of rotation of the frame about the shaft.
=
Moreover, U.S. app. no. 2002/0070598 shows a swivel armrest providing the
pivoting
armrest to allow multi-position adjustment.
=
Furthermore U.S. Patent No. 6,168,237 teaches an armrest construction for
chairs which
includes an armrest support having a lower end constructed for attachment to a
chair, an
upper end and a pivoting block attached to the upper end.
Furthermore U.S. Patent No. 7,029,049 teaches an adjustable armrest and a
method of
inhibiting the movement of an armrest.
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Finally, U.S. Patent No. 6,948,775 relates to an armrest which includes a
support rod, a base,
a locating seat, a mounting seat and an upper cover wherein the base has a
chamber having at
least one guide rail, each provided with engagement grooves.
These and other prior art armrests present relatively complicated structures.
Furthermore it is not uncommon for a user to apply their weight against the
armrests as the
user rises from the chair. One of the difficulties experienced by prior art
armrests resides in
the instability which is exhibited during the application of force against the
armrests when the
user rises. It is not uncommon for these rotatable armrests to "give" and
rotate unnecessarily
during this action which can cause the user instability while rising.
In other words it is not uncommon for these armrests to rotate laterally
outwardly from the =
chair, causing the users arms to move outwardly while rising. In other words,
the rotatable
armrests tend to laterally rotate about a vertical access of rotation.
Accordingly, there is a need to provide rotatable armrests which inhibit
unwanted rotation
while at the same time permitting rotation when the user is seated.
Disclosure of Invention
Accordingly it is an aspect of this invention to provide an armrest for a
chair having a first
member connected to the chair; a second member selectively rotatable relative
to the first
member; and structure disposed between the first and second members for
resisting the
rotational movement between the first and second members.
In one aspect of this invention the first and second members include low
density plastic
material which resists movement therebetween. In a further embodiment, high
density plastic
material is provided between the first and second members to permit selective
rotational
movement between the first and second members at selected intervals.
It is another aspect of this invention to provide damper structure between the
first and second
members for resisting rotational movement of the first member relative to the
second member
about an axis of rotation. In one embodiment of the invention the damper
structure comprises
a torque resistor disposed about the axis of rotation. The torque resistor can
comprise a first
portion which is engageable with the first member and a second portion which
is engageable
with the second member and a shaft disposed between the first and second
portions of the
torque resistor.
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It is also an aspect of this invention to provide a method of rotating an
armrest about a
vertical support connected to a chair which comprises disposing a torque
resistor structure
between the vertical support and the armrest for resisting rotational movement
about the axis
of rotation when the armrest is pushed against the vertical support and for
permitting the
rotation of the armrest relative to the vertical support beyond the selected
level.
These and other objects and features of the invention shall now be described
in relation to the
=
following drawings.
Brief Description of Drawings
Fig. 1 is a representative drawing of a chair having an armrest.
Fig. 2 is a top plan view of a first plate having spaced projections.
Fig. 3 is a side view of figure 2.
Fig. 4 is a top plan view of a second plate having spaced depressions for
receiving the spaced
projections of the first plate.
Fig. 5 is a side view of figure 4.
Fig. 6 is a partial cross-sectional view of one embodiment of the invention.
Fig. 7 is a partial cross-sectional view of another embodiment of the
invention.
Fig. 8 is a perspective view of a torque resistor.
=
Fig. 9 is a partial cross-sectional view of the armrest assembly showing the
torque resistor in
place.
Best Mode for Carrying Out the Invention
= 25 In the description which follows, like parts are marked throughout
the specification and the
drawings with the same respective reference numerals. The drawings are not
necessarily to
scale and in some instances proportions may have been exaggerated in order to
more clearly
depict certain features of the invention.
= Figure 1 illustrates a typical chair 1 having a backrest 3 and a seat 5.
Furthermore the chair 1
can include adjustment means 9 which comprise of adjustment structure 7 having
adjustment
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levers 11 which are individually numbered 13, 15 and 17 so as to adjust the
chair in a manner
well know to those persons skilled in the art.
The chair also includes a pedestal 7.
The armrest 2 comprises of a first member 22 connected to the chair and a
second member 50
which is selectively rotatable relative to the first member 22 about the
vertical axis V.
Means 45 is disposed between the first member 22 and second member 50 for
resisting the
rotational movement between the first and second members.
In one embodiment of the invention the means 45 for resisting the rotational
movement
between the first 22 and second 50 members comprises:
(a) one of the first 22 and second 50 members including low density plastic
material;
(b) first and second plates 30 and 40.
Fig. 2 illustrates a first plate 30 having spaced projections 32. In the
embodiment shown in
figures 2 and 3 the spaced projections are equally disposed radially about an
angle a as
shown. Any number of projections 32 can be utilized. The first plate 30 can be
secured to
the first member 22 in any number of ways including fastening means, adhesive
or other
means.
Figures 4 and 5 illustrate an embodiment of the second plate 40 which includes
a plurality of
recesses 42 adapted to receive the projections 32 when the second plate 40 is
superimposed
about an axis of rotation V as shown in the drawings. The second plate 40 is
secured to the
underside of the second member or armrest 50 as best illustrated in figure 6.
In another,
embodiment, first plate 30 can be associated with second member 50 and second
plate 40 can
be associated with first member 22.
Figure 6 illustrates one embodiment of the invention whereby the second member
or armrest
50 comprises of low density plastic material which is deformable when pressure
P is applied
thereto. The deformability of second member or armrest 50 is shown by the
hidden lines of
figure 6. Accordingly the hidden lines of figure 6 illustrate the
deformability of the second
member when a user rises from the chair thereby applying the user's weight by
pressure P so
as to deform the second member. When the second member 50 which comprises of
soft
plastic material deforms, the low density plastic material pushes against the
upper surface 31
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of the first plate 30 as shown. The first and second plates 30 and 40
respectively comprise of
a harder material which is generally not deformable upon the application of
pressure P.
Accordingly the soft or low density plastic material is pushed against the
high density
material 30 therefore the armrests 50 tends to "grip" and resist rotation R
under this
condition. The low density plastic material deforms beyond the exterior extent
of the second
plate 40 as shown in figure 3. The first and second plates can be comprises of
any number of
materials including metal or high density plastic material.
When a user is in a chair, the low density plastic material moves from the
dotted lines shown
in figure 6 to the solid lines shown in figure 6 thereby permitting rotation
of the second plate
40 relative to the first plate 30, or in other words the second member or
armrest 50 relative to
the first member 22. Since the first plate 30 includes projections 32 relative
to the second
plate 40 a user is able to selectively rotate the armrest 50 relative to the
first member 22 so
that the projections 32 sequentially move into the recesses 42 at selective
intervals at an angle
a in a detent fashion. Accordingly the projections 32 and recesses 42
illustrate detent means
so that the user is able to rotate the armrest laterally about the vertical
axis V at selected
intervals defined by angle a.
The radial extent of the second plate 40 is smaller than the radial extent of
the first plate 30 as
shown in figure 3 so as to provide a region for the extremities 51 of second
member 50 to
deform and contact the upper surface 31 of the first plate 30 as shown.
Figure 7 shows another embodiment of the invention whereby the radial extent
of both the
first and second plates 30 and 40 are substantially the same. However, the
first member 22
also includes at its upper end 21 a lower armrest 55 which is connected to the
first support
member 22 by any number of means including fastening, gluing, welding or the
like. The
lower armrest member 55 includes the first plate 30 which is connected thereto
by means of=
fasteners that are adapted to be received by the holes 53 and secured thereto.
The upper
armrest member 50 also includes a second plate 40 which is secured thereto by
any number
of means including fasteners which are adapted to be secured through the holes
43. The first
and second plates 30 and 40 comprise of a material which is substantially non-
deformable
such as metal or high density plastic material. The upper and lower armrest
portions 50 and
55 comprise low density material which is deformable as shown by the hidden
lines.
Accordingly upon the application of pressure P when a user pushes down on the
armrests
when rising from the chair the upper and lower low density plastic material
will deform as
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shown causing the upper and lower armrest portions 50 and 55 "grip" one
another
substantially resisting rotation of the armrests in this position.
During resting of the user in the chair pressure P is alleviated causing the
deformable
portions of the upper and lower armrests 50 and 55 to relax and move back to
the original
position as shown by the solid lines of figure 5; thereby permitting rotation
of the upper
armrest portion 50 relative to the lower portion 55 as previously described.
Figures 8 and 9 illustrate another embodiment of the invention whereby the
means for
resisting rotational movement 45 is disposed between the first and second
members 22 and 50
for resisting the rotational movement between the first and second members 22
and 50
comprise damper means. The damper means comprise a torque resistor disposed
about an
axis of rotation V which are generally available in the marketplace. For
example, a hinged
damper is available from Illinois Tool Inc. as Delpro part number 43-005033.
Furthermore
Reel Precision Manufacturing Corporation of St. Paul, MN sell frictional
torque restrictors or
hinges with the designation T1220 frictional torque hinge. Other torque
restrictors are also
available.
The torque restrictor illustrated in figure 8 comprises a first torque portion
102 and a second
torque portion 100 which are rotatable relative to one another about the shaft
108 in a manner
well known to those persons skilled in the art. The first torque portion 102
includes a pair or
= wings 106 or projections extending outwardly therefrom while the second
torque portion 100
includes a second pair of wings or projections 104 as shown.
The first member 22 includes a hole or bore 23 for receiving the first torque
portion 102 as
= shown. Moreover the bore or hole 23 also includes a plurality of slots 25
which are adapted
to receive the wings 106 so as to fixedly retain the first portion 102
relative to the first
member 22.
Moreover the second member or armrest 50 also includes a second hole or bore
27 which is
adapted to receive the second torque portion 100 as shown. The second hole or
bore 27 also
includes a plurality of slots 29 which are adapted to receive the wings 104 so
as to fixedly
retain the second torque portion 100 relative to the second member or armrest
50 as shown.
The second member or armrest 50 in the embodiment shown in figure 5 can
comprise of a
non-deformable material such as high density plastic material so as to fixedly
secure the
torque restrictor even under the application of pressure P. Accordingly, in
the embodiment
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shown in figure 9 a user can selectively rotate the second member or armrest
50 about arc R
as shown upon the application of lateral force. The torque restrictor is
selected so as to resist
rotation of the armrest 50 at a selected level. Accordingly the armrest will
not move even
when a user is in a seated position until sufficient force is applied to the
second member or
armrest 50 beyond the selected level of torque resistance so as to permit
rotation of the
second member 50 about the first member 22. Accordingly when a user raises the
second
member or armrest 50 will tend to resist the rotation of the armrest thereby
providing better
stability during this operation.
Furthermore the torque resistor provides a circumferential resistance or
radial resistance to
rotation (rather than axial) which exhibits little backlash or springback and
holds the position
in a desired location. Furthermore the resistors do not loosen appreciatively
over time and
provide a substantially constant torque over time. Moreover the torque
resistors offer
excellent resistance to the wanted rotation of the second member 50 relative
to the first
member 22 when a sudden force is applied thereby exhibiting excellent
resistance to rotation.
However, upon the application of a slow or constant force a user seated in the
chair is able to
rotate the armrest 50 to a desired position.
Figure 9 therefore discloses a method of rotating an armrest about a vertical
support
connected to a chair comprising disposing a torque resistor between the
vertical support and
the armrest for resisting rotational movement about the axis of rotation when
the armrest is
pushed against the vertical support and for permitting the rotation of the
armrest relative to
the vertical support beyond the selected level.
Moreover the earlier embodiments described above also include a method of
rotating an
armrest about a vertical support connected to a chair which comprises
utilizing low density
plastic material and high density plastic material between the vertical
support and the armrest
for resisting rotational movement about the axis of rotation when the armrest
is pushed
against the vertical support and from permitting the rotation of the armrest
relative to the
vertical support beyond the selected level.
It should be appreciated that the torque resistor as described .herein can
also be utilized in
combination with the first embodiments described herein so as to provide
excellent resistance
to the undesireable rotation of the armrest about a vertical support.
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Moreover it is possible to utilize different strengths of torque resistors in
each of the arms 50
which accompany a chair.
12241783.1
