Note: Descriptions are shown in the official language in which they were submitted.
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LATERAL ADJUSTMENT MR~ANISM FOR A C~AIR ARMR~.~ T
Background of the Invention
1. Field of the Invention
This invention relates to a lateral adjustment
5 mechanism for a chair armrest.
2. Description of the Related Art
Office chairs are typically adjustable so that they may
accommodate a wide range of users. In this regard, one desirable
adjustment is the width between the chair armrests. A known
mechanism permitting such adjustment comprises a bracket mounted
underneath the chair seat with a slot receiving a lateral
extension of an armrest support member. A post extends through
both openings in the bracket and a slot which runs along the
lateral extension in the support. A large knob is threaded to
15 the post so that it abuts the support and pushes the support
against the back of the bracket, thereby frictionally locking the
support to the bracket. To laterally adjust the armrest, the
knob is loosened, the armrest support pulled or pushed to an
appropriate lateral position, and the knob then tightened to lock
the support - and the armrest - in its new lateral position.
Because this mechanism relies on friction for locking, the knob
must be made relatively large to allow the user a sufficient
moment arm. Even so, two-handed operation of the knob is often
required. In any event, adjustment while seated is difficult.
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Furthermore, adjustment is a multi-step process: loosening the
knob, moving the support, then tightening the knob.
There is therefore a need for a lateral adjustment
mechanism which permits easy one-handed operation while seated.
There is also a need for a versatile apparatus adapted to permit
construction of different adjustment mechanisms.
Summary of the Invention
According to the present invention, there is provided
a lateral adjustment mechanism for a chair armrest, comprising
the following: an armrest support having an upstanding portion
and a lateral extension, said lateral extension having an opening
extending therealong and a rack of teeth extending therealong and
projecting into said opening; a bracket adapted for mounting
underneath a chair seat, said bracket having a slot slidably
receiving said lateral extension of said armrest support; a bar
within said armrest support opening biased into blocking relation
with said teeth; a knob having a pair of depending pins extending
through an aperture in said bracket and received within spaces
between the teeth of said rack; whereby, when said knob is
turned, said pins walk along said rack such that said armrest
support moves with respect to said bracket.
According to another aspect of this invention, there
is provided a bracket for a lateral adjustment mechanism for a
chair armrest comprising the following: means for mounting said
bracket underneath a chair seat; a slot for reception of a
lateral extension of an armrest support, said armrest support of
the type having an armrest support opening extending along said
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lateral extension; a first aperture extending through a face of
said bracket to said bracket slot, said first aperture adapted
for reception of walking pins whereby said bracket slot may
receive an armrest support with a rack of teeth extending along
said lateral extension and projecting into said armrest support
opening, said rack of teeth for receiving said walking pins, and
with a bar within said armrest support opening biased into
blocking relation with said teeth; a second aperture extending
through said face of said bracket, said aperture being non~
circular and adapted for reception of a post having a threaded
end and a non-circular cross-section such that said post is held
against rotation when within said aperture, whereby said bracket
slot may receive an armrest support with an armrest support
opening, said second aperture and said armrest support opening
may receive said post, and a knob may be threaded onto said post
into abutting relation with said armrest support in order to
frictionally lock said armrest support between said knob and said
bracket.
Description of the Drawings
In the figures which disclose example embodiments of
the invention,
Figure 1 is an exploded perspective view of a lateral
adjustment mechanism made in accordance with this invention,
Figure 2 is a front view of the adjustment mechanism
of Figure 1 seen from the direction of the number 2 in Figure 1,
Figure 3 is a cross-sectional view along the lines 3-
3 of Figure 1,
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Figure 4 is a cross-sectional view of the mechanism of
Figure 1 shown in operation,
Figure 5 is a cross-sectional view of the mechanism of
Figure 1 shown in operation,
Figure 6 is a exploded perspective view of another
adjustment mechanism made in accordance with this invention, and
Figure 7 is a cross-sectional view along the lines 7-
7 of Figure 6.
Detailed Description of the Preferred Embodiments
Turning to Figure 1, a lateral adjustment mechanism
illustrated generally at 10 comprises an armrest support 12
having an upstanding portion 14 and a lateral extension 16.
Referencing Figure 3 as well as Figure 1, the lateral extension
has an opening 18 extending therealong and a rack of teeth 20
extending along, and projecting into, opening 18. A bracket 24
has a slot 30 which slidably receives the lateral extension 16
of armrest support 12. Bracket 24 has flanges 26 (Figure 1) with
bolt receiving openings 28 (Figure 1) which adapt the bracket for
mounting underneath a chair seat.
As best seen in Figure 3, a bar 34 within the armrest
support opening 18 is biased by a spring 36, which acts between
wall 38 of bracket 24 and the bar 34, into blocking relation with
the rack of teeth 20.
A knob 40 has a pair of depending pins 42a, 42b
extending through an aperture 44 in the bracket 24. The
depending pins 42a, 42b are received within spaces 48 between the
teeth 50 of the rack of teeth 20.
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With reference to Figure 2, knob 40 has four
circumferentially equally spaced finger receiving notches 52.
As will be apparent from that Figure, each of these notches is
radiused.
5Returning to Figure 1, a back plate 56 is received by
a recess 58 in bracket 24. Screws 60 received in shouldered
openings 62 of the back plate and are threaded into threaded
openings in pins 42a, 42b so that the back plate 56 holds the
knob 40 in place.
10In operation, referencing Figure 2, a user sitting in
a chair to which bracket 24 has been attached may reach under the
chair seat and grasp knob 40. The four radiused notches 52 allow
the knob to be grasped comfortably with little re-orientation of
the user's natural hand position. The user may then turn the
15knob. Referring to Figure 4, if the knob is rotated in a
clockwise sense, it rotates about pin 42a so that pin 42b leaves
its space 48 between teeth 50 at one side of pin 42a.
Referencing Figure 5, pin 42b continues to move while the knob
is rotated until pin 42b enters a space 50 which is at the
20opposite side of pin 42a. At this point the knob has rotated
through 180 degrees. Clearly, the knob 40 may be turned
clockwise or counterclockwise, as desired, and will alternately
rotate about pins 42a and 42b as the knob is turned in one sense.
Consequently, pins 42a, 42b "walk" as the knob is rotated in one
25sense, therefore, these pins may be described as "walking pins".
Walls 17 and 19 limit rotation of the knob when one of the pins
comes into abutment with one of these walls. Because knob 40 is
laterally fixed with respect to bracket 24 and the bracket is
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fixed underneath a chair seat, it is the rack of teeth 20 which
must move laterally when knob 40 is turned. However, the rack
is fixed with respect to the armrest support 12.
Consequently, turning knob 40 moves the armrest support 12
laterally.
It will be noted from Figure 4 that bar 34 is displaced
by a pin against the urging of spring 36 when the knob 40 is
turned. The bar and spring therefore act to latch the lateral
adjustment mechanism until knob 40 is turned.
As will be apparent to anyone who reaches under a chair
while seated, the range of rotational motion of the hand allowed
by human joints is limited. Furthermore, the torque which may
be imparted is also more limited in this position. It will be
apparent to those skilled in the art that the provision of the
multi-notched knob 40 facilitates lateral adjustment of the
armrest even given the limited rotational freedom of a user's
hand. Furthermore, the torque required to turn knob 40 of
adjustment mechanism 10 is sufficiently low that adjustment while
seated is easily accomplished. This is in contrast to an
adjustment mechanism relying upon a friction lock.
With reference to Figures 1 and 2, bracket 24 also has
an opening 66 through its back face 68 and an opening 70 through
its front face 72. Opening 66 has a square cross-section.
Opening 66 and 70 adapt bracket 20 for use with a second lateral
adjustment mechanism as is described here following.
Turning to Figures 6 and 7, armrest support 112 of
armrest adjustment mechanism 110 has an upstanding portion 114
and a lateral extension 116. The lateral extension has a slot
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118 extending therealong. A post 180 extends through opening 66
of the back face 68 of bracket 24, slot 118 of armrest support
112, and opening 70 of the front face 72 of bracket 24. The post
has a square cross-sectional portion 182 which is received within
opening 66 in order to lock the post 180 against rotation. Post
180 also has a threaded end 184 for reception of knob 186. Knob
186 has a reduced diameter portion 188 which has a diameter less
than that of opening 70 through the front face of bracket 24.
Accordingly, when knob 186 is threaded down on post 180, the
10reduced diameter portion 188 extends through opening 70 and abuts
the lateral extension 116 of armrest support 112 on either side
of slot 118. By tightening knob 186, the lateral extension 116
is therefore sandwiched between the knob and the inside back face
of bracket 24 and frictionally locked in place.
15In operation, knob 186 may be loosened, the armrest
support 112 moved laterally as desired and then knob 186
retightened. The lateral adjustment mechanism 110 is of simpler
construction than that of mechanism 10 of Figure 1 so as to
provide a less expensive option. It is not, however, preferred
as one-handed operation while seated is not facilitated.
Nevertheless, bracket 24 may be used in either mechanism 10 of
Figure 1 or mechanism 110 of Figure 6 which reduces overall
manufacturing costs.
Bracket 24 and armrest support 12 (of Figure 1) and 112
(of Figure 6) are preferably made of glass reinforced nylon.
This is particularly useful in mechanism 110 of Figure 6 as glass
reinforced nylon has a higher coefficient of friction than many
other materials, such as steel, thereby enhancing frictional
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locking between the bracket and the armrest support.
Modifications with be apparent to those skilled in the
art and, therefore, the invention is defined in the claims.
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