Note: Descriptions are shown in the official language in which they were submitted.
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FIELD OF THE INVENTION
The present invention relates to height
adjustment mechanisms for chair armrests and more
particularly to synchronous and non-synchronous armrest
height adjustment mechanisms.
BACKGROUND OF T~E INVENTION
Comfortable and user friendly office equipment
which can be readily adapted to a user's individual needs
is a prerequisite for creating an office work environment
conducive to maximum productivity. Office chairs are an
integral part of any office environment and chairs having
features which can be adjusted to meet a user's
requirements with respect to posture clearly play a pivotal
role in contributing to a user's comfort level.
Chairs having height adjustable armrests are
important for meeting both the posture and functional
requirements of the user, the latter relating to the
particular task to which the user is attending, such as
keyboarding, reading or writing which may all require
chairs with armrests at different heights.
United States patent No. 4,951,991 discloses an
armrest height adjustment mechanism for a chair which
provides synchronous, simultaneous vertical movement of
both armrests in the same direction upon moving one of the
armrests. The armrests of chairs fitted with these height
adjustment mechanisms are interconnected by a spiralled
cable and jacket assembly one end of which is connected to
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a first armrest. The cable extends down through the first
armrest support, under the chair and up the other armrest
with the other end of the spiralled cable engaged with a
rotatably mounted circular gear. A spiralled rod is
attached at one end to the second armrest and extends
downwardly therefrom and is engaged with the gear on the
other side thereof. When the first armrest is pulled up the
free end of the cable is pulled downwardly so that the gear
is rotated thereby driving the spiralled rod and hence the
second armrest upwardly.
A drawback to this arrangement is that the
armrests are only designed to be synchronously tied
together so that the armrests cannot be independently
operated. Another drawback is the need for relatively
expensive spiralled cables and rods which must be properly
sized to mesh with the gear in order to prevent seizing or
jamming of the adjustment mechanism over the lifetime of
the chair. Accordingly, it would be desirable to provide
an armrest height adjustment mechanism which can be adapted
to provide either synchronous or non-synchronous armrest
height adjustment, is economical to produce and is
relatively maintenance free.
SUMMARY OF T~E INVENTION
The subject invention provides a height
adjustment mechanism for chair armrests. In one aspect of
the invention a height adjustment mechanism for chair
armrests includes a pair of armrest support members
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attachable to a chair in spaced relation. A pair of
armrests is slidably mounted for vertical movement one on
each of the armrest support members. Included are two
independent locking means operably coupling each armrest to
each associated armrest support member for releasably
locking each armrest with respect to its associated armrest
support member. The locking means of each armrest includes
a locking member mounted on the armrest support member and
a latch member operably mounted on the armrest. The latch
0 member is movable to releasably engage the locking member.
In this particular aspect of the invention, the
height adjustment mechanism may include means
interconnecting the armrests for translating vertical
movement of one armrest into synchronized vertical movement
5 of the other armrest.
In another aspect of the invention there is
provided a chair having height adjustable armrests, which
includes a chair base and a chair backing member attached
to said chair base. A chair seat is mounted to the chair
base and a pair of spaced armrests are provided. The
chair is provided with an armrest height adjustment
mechanism which includes a pair of armrest support members
attachable to a chair in spaced relation, the armrests each
slidably mounted for vertical movement one on each of said
armrest support members, the armrest height adjustment
mechanism including two independent locking means one
associated with each armrest for releasably locking each
armrest with respect to its associated armrest support
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member, the locking means of each armrest including a
locking member mounted on the armrest support member and a
latch member operably mounted on the armrest, the latch
member being movable to releasably engage said locking
member.
In this particular aspect of the invention, the
chair may include means interconnecting the armrests for
translating vertical movement of one armrest into
synchronized vertical movement of the other armrest.
BRIEF DESCRIPTION OF THE DR~WINGS
The following is a description, by way of example
only, of various embodiments of the armrest height
adjustment mechanism forming the subject invention,
reference being had to the accompanying drawings, in which:
Figure 1 is a perspective view o:E a chair
provided with a pair of armrests and associated armrest
height adjustment mechanisms;
Figure 2 is a front elevational view, broken
away, of a chair provided with the armrest raising and
lowering mechanism of Figure 1;
Figure 3 is a perspective view of a portion of
one armrest support in which is enclosed an armrest raising
and lowering mechanism;
Figure 4 is an exploded view of a first
embodiment of an armrest raising and lowering mechanism
contained within the armrest support shown in Figure 3;
Figure 5 is a sectional view taken along the line
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5-5 of Figure 3;
Figure 6a is a sectional view taken along the
line 6-6 of Figure 3 showing the armrest in the lowered
position and Figure 6b is a simllar view showing the
armrest in a raised position;
Figure 7 is a front elevation sectional view of
a second embodiment of the armrest height adjustment
mechanism forming part of the subject invention;
Figure 8 is a perspective view of a portion of
the armrest height adjustment mechanism of Figure 7; and
Figure 9 shows a more detailed view of the
encircled portion 9 of Figure 8.
DETAILED DESCRIPTION OF THE INVENTION
Referring first to Figure 1 there is shown a
chair 20 of the type generally found in an office
environment. The chair includes a base provided with
supporting legs 22 each having a castor 24 attached at a
lower end thereof. Legs 22 extend radially from a spindle
support 2~ which supports a spindle 28 which in turn is
attached to a chair seat support not shown. A seat 30 is
mounted on the seat support. Chair 20 also includes a back
rest 32 and a pair of spaced armrests 34 each mounted on an
armrest support which comprises an arm cover 36 mounted on
an L-shaped channel support 38. Armrests 34 are height
adjustable in the vertical direction relative to a chair
supporting surface as indicated by arrow A (see ghost
outline of the armrest in a raised position). The height
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adjustment mechanism which facilitates the raising and
lowering of armrests 34 is located in the interior of
channel supports 38 and will be discussed herebelow.
Referring now to Figures 1 to 6, an armrest
height adjustment mechanism 40 includes the generally L-
shaped armrest support channel 38 which is provided with
two arms 42 and 44 and an open channel 46, best seen in
Figure 4. Each channel support 38 is provided with a
mounting plate 48 attached to arms 44 whereby the raising
and lowering mechanism is mounted on chair 20 by bolting
mounting plate 48 to the bottom of the chair seat support.
Because the two armrest supports are mounted independently
to the chair they can be spaced apart the desired distance.
Height adjustment mechanism 40 comprises the pair of arm
covers 36 slidably mounted over the vertically extending
arms 42 of support channels 38. Arm covers 36 may be
fabricated of moulded plastic to any aesthetically pleasing
shape.
Referring specifically to Figures 3 to 6, height
adjustment mechanism 40 includes a ratchet track 52 which
is received into open channel 46 of support channel 40 and
secured to the support channel by screws 54. Ratchet track
52 includes a tracked portion 56 which is located adjacent
the upper end of arm 42 of the support channel. Tracked
portion 56 includes a plurality of spaced grooves 58 which
extend transversely thereacross.
Arm cover 36 includes a flange 62 located at the
upper end thereof which is integrally formed therewith and
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which extends outwardly therefrom. A pair of spaced and
countersunk apertures 64 are provided in flange 62 for
securing armrest 34 to arm cover 36. Arm cover 36 is
provided with a generally rectangular aperture 66 located
just below flange 62. Arm cover 36 also includes an L-
shaped slider plate 70 having two arms 72 and 74 with arm
72 provided with spaced cut-outs 76 and a pair of spaced
apertures 78. Plate 70 is attached to the upper end of arm
cover 36 via screws, not shown, extending through cut-outs
76 in plate 70 and threadably received into threaded
apertures 80 in the arm cover. A slider 82 is located on
the hollow interior of arm 42 and has the shape of a tuning
fork, best seen in Figure 4. The two arms of slider 82
include threaded bores 84 at the free ends thereof which
are collinear with the arms. Slider 82 includes a cross
member 86 joining the arms of the slider, and the cross
member includes a threaded bore 88 extending therethrough.
Slider 82 is rigidly secured to slider plate 70 by a pair
of screws, not shown, inserted through apertures 78 in
plate 70 whereby the screws are received by bores 84 in the
slider. The relative positioning of slider 82 with respect
to tracked portion 56 of the ratchet track is best seen in
Figure 5.
Height adjustment mechanism 40 includes a latch
90 having a latch arm 92 provided with a finger actuable
portion 94 integrally formed therewith at one end of arm 92
and a laterally extending tongue 96 integrally formed
therewith at the other end of the arm. Latch 90 is
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provided with a pivot rod 98 secured thereto with the ends
of rod 98 being received by a pair of spaced guide slots
100 located in the upper end of arm cover 36 adjacent
flange 62, best seen in Figure 4. Latch 90 is mounted to
arm cover 36 with portion 94 located in aperture 66 with
pivot rod 98 retained in guide slots 100 by the edge of arm
74 of the slider plate. Rod 98 is free to rotate about its
longitudinal axis. Mechanism 40 includes a leaf spring 102
located between finger actuable portion 94 of latch 90 and
arm 74 of slider plate 70. Spring 102 acts to bias tongue
96 of the latch into engagement with tracked portion 56 of
the ratchet track.
In one embodiment of the armrest height
adjustment mechanism forming the present invention, the
height adjustment mechanism located in each of the two
spaced channel supports on the chair are independently
operable to form what will hereinafter be referred to as
the non-synchronous embodiment. Referring to Figure 6, the
operation of the non-synchronous embodiment will now be
discussed with respect to only one of the armrests but
bearing in mind that both work in exactly the same way.
Figure 6a shows armrest 34 in the lowest pOSitiOII wherein
end portion 96 of latch 90 is engaged in the lowermost
groove 58 of track 56 thereby preventing movement of arm
cover 36 and hence armrest 34. In order to raise armrest
34, the user presses inwardly on the finger actuated
portion 96 of latch 90 thereby causing latch arm 92 and end
portion 96 to pivot about pivot rod 98 away from track0d
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portion 56. Once latch 90 is disengaged from tracked
portion 56, thereby unlocking the armrest, the user lifts
armrest 34 with the latch portion 94 still pushed inwards
whereby arm cover 36 slides vertically upwards. When the
user has moved armrest 34 to the desired height, latch 90
is released and latch 90 pivots about pivot rod 98 back
into engagement with tracked portion 56 thereby locking
armrest 34 at the desired height, (see Figure 6b). To
lower the armrests the identical procedure is followed
except that once unlocked the armrests are lowered to the
desired position. In this non-synchronous embodiment the
two armrests may be operated independent of each other.
In another embodiment of the armrest height
adjustment mechanism, the two armrests are operably coupled
together in such a way that the action of raising one
armrest serves to raise the other armrest when the latter
is unlocked. This embodiment is hereinafter referred to as
the synchronous height adjustment mechanism. Referring to
Figures 4 and 7-9, the synchronous mechanism includes a
lower toothed guide spool 110 and an upper toothed guide
spool 112 secured to each of the ratchet tracks 52 located
in each of the channel supports 40, with one spool of each
pair located above the other in the particular channel
support. Spools 110 and 112 are snap fitted into cut-outs
113 located in the lower portion of ratchet tracks 52, best
seen in Figure 4. Spools 110 and 112 are rotatably movable
in cut-outs 1130 The synchronous height adjustment
mechanism includes an elongate strap 114, a spring 116, a
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strap lock plate 118 and a strap lock cap 120. Strap 114
is connected at one end 122 to one end o~ spring 116 and
extends upwardly on the interior of one channel support 38
to loop over the upper guide spool 112 and extend
downwardly in the channel support through arms 44 below the
spring. The strap also extends up the other channel
support 38 and i5 looped over the upper guide spool 112 and
back down the channel support into arm 44 where it is
engaged with one side of strap lock plate 118. The other
side of strap lock plate 118 is attached to the other end
of spring 116. The lower guide spools 110 are positioned
in such a way that strap 114 is maintained in a spaced loop
configuration in lower arms 44 and between the two armrest
supports under the seat support.
Strap 114 is secured to each of sliders 82 at 130
and 132 by fasteners 134 threadably engaged in threaded
bores 88 located in the slider cross members 86. In one of
the channel supports strap 114 is attached to the
associated slider on the inner portion of the strap loop
while in the other channel support the strap is attached to
the slider on the outside of the loop (see Figure 8). The
end of strap 114 engaged in lock plate 118 is pulled and
adjusted to the desired tension whereupon lock cap 120 is
secured to lock plate 118 in such a way that a portion of
strap 114 is compressed between plate 118 and lock cap 120,
thereby locking the strap at the desired tension.
In operation, in order to raise both armrests 34
the user pushes inwardly on the finger actuated portions 94
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of latches 90 mounted in the arm covers 36. Once both
armrests are unlocked by disengaging end portions 96 from
their respective grooves, one of the armrests is raised
whereby the associated slider 82 is pulled upwardly to the
desired height. When one armrest 34 is pulled upwardly,
the upward movement of the associated slider 82 causes
spring 116 to extend by virtue of its connection to the
slider. Simultaneously, the other end of strap 114
attached to lock plate 118 is pulled inwardly by the
restoring force developed in extended spring 116 which acts
to pull the slider 82 in the other channel support 38
upwardly at the same time. In this way the user need only
exert a lifting force on just one of the armrests after
both have been unlocked in order to raise both. When the
armrests 34 have been lifted to the desired height the user
releases finger portions 94 of latches 90 whereby the end
portions 96 of the latter pivot back into engagement wi-th
a groove 58 of the track portion 56 thereby locking
armrests 34 at the desired height. In order to lower
armrests 34, the armrests are unlocked as described above
whereupon the extended spring 116 acts to pull both sliders
76 downwardly in their respective channels. When armrests
34 have been lowered to the desired height, the latches 90
are released thereby locking the armrests in place. Spring
116 is of a strength sufficient to be overcome by a user
lifting on the unlocked armrests without having to exert
undue force.
It will be appreciated by those skilled in the
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art that the armrests and armrest height adjustment
mechanism forming the subject invention may be integrated
into a chair at the time of manufacture of the chair or
alternatively they may be manufactured as a separate unit
and retrofitted into a chair as described above.
While the height adjustment mechanism for chair
armrests forming the present invention has been described
and illustrated with specific reference to the various
embodiments, it will be appreciated that numerous
variations of these embodiments may be made without
departing from the scope of the invention described herein.
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