Note: Descriptions are shown in the official language in which they were submitted.
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ERGONOMIC CHAIR
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention generally relates to a device for supporting a user in a seated
position, and
in one preferred embodiment, to a chair of the reclining back type. In another
preferred
embodiment, this invention relates to a chair having automatically adjusting
armrests. In a
further preferred embodiment, this invention relates to a chair having an
adjustable headrest. In a
still further preferred embodiment, this invention relates to a chair having
an automatically
adjusting resistance to tilting that increases in proportion to the weight of
the user and as the tilt
angle is increased. In a yet further preferred embodiment, the chair has a
tilting mechanism
which changes the angle of the seat and its support and increases the chair's
angle of maximum
recline, as well as providing a forward tilting position.
2. Description of the Related Art
Reclining type chairs commonly used in offices usually provide for the back to
recline
alone, for the seat and back to recline as a unit, or the seat back may
recline in a coordinated
proportion with the seat. If the back alone pivots, it generally creates a
problem known as "shirt
tail pull." This problem is particularly acute if the pivot of the chair back
is not coordinated with
the natural body action. This problem can also be accentuated by the tendency
of the hips of the
user to slide forward as the back tilts rearwardly.
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In chairs where both the seat and back recline as a unit, in the reclined
position there is a
tendency to lift the legs of the user from the floor creating an undue
pressure by the forward edge
of the seat against the underside of the legs of the user immediately above
the knee. To overcome
this problem the pivot point of the reclining action may be moved forward
sufficiently to permit
the user's feet to stay on the floor. The undesirable effect of this
arrangement is that the body
angle between the user's torso and legs is unchanged and as a result, the
user's eye level drops
undesirably when the chair is reclined.
In any reclining chair, it is desirable that the recline pivot point be at the
center of the
body or where the user's back normally pivots (i.e., an axis through the
user's hip joints). The
pivot point of a reclining chair is normally displaced from the ideal pivot
point. It is also
desirable to have a chair wherein the angle between the user's torso and his
legs opens up to
relieve internal congestive body pressures. It is, of course, also desirable
to provide a chair
wherein the user's feet remain on the floor and the recline action parallels
the natural body action
closely enough to avoid the common shirt tail pull problem.
It is also desirable to provide a chair which is of simplified construction
and yet of clean,
pleasing appearance emphasizing the isolated and separate appearance of the
seat and back with
respect to the supporting frames.
My earlier U.S. patent No. 4,429,917 shows one approach to solving these
problems.
U.S. Patent No. 4,943,114 to Piretti allegedly reports a chair with a compact
backrest
linkage mechanism that enables the chair backrest and seat to recline.
U.S. Patent No. 5,251,958 to Roericht et al. allegedly reports a chair with a
synchronous
adjusting device that uses the weight of the user to provide a restoring force
to return the chair
back to an upright position after a user has reclined in the chair.
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U.S. Patent No. 5,486,035 to Koepke, et al., asserts, without providing any
showing, that
" In such constructions, the difficulty of reclining the chair, i.e.,
generating the reclining force,
increases the further the chair is reclined, and it is common to employ
adjusting apparatus for
increasing or decreasing the reclining tension of a chair, such adjusting
apparatus changing the
tension of a spring, or otherwise modifying the reclining mechanism." Col. 1,
1. 29-34.
While chairs with arms are well known in the art, heretofore, the arms have
been either
fixed, or adjustable. If the arms were adjustable, any adjustments have been
less than ideal
and/or quite cumbersome.
Additionally, it was known in the art to put a headrest on a chair, including
a reclinable
chair. However, such headrests typically provided the chair occupant with very
little support,
i.e., when the chair is reclined, the headrest maintains its position relative
to the back of the chair.
Alternatively, if the headrest were to provide the chair occupant with
substantial support, the
headrest required awkward adjustments.
Moreover, while it is believed that some reclining chairs heretofore available
have had a
means to adjust their resistance to reclining, such adjustments have been less
than ideal, and/or
very cumbersome and not practicable.
Instead, rather than confront the processes necessary to adjust their chairs
to fit the needs
of their particular body build, most users of chairs use them without making
any adjustments.
Consequently, any ergometric advantages that might be delivered by the
properly tuned chair are
not achieved. Thus, there remains a need for a chair that is adjustable to the
needs of the
individual chair occupant without requiring any substantial effort on the
occupant's part to effect
the adjustments. In other words, a substantially self-adjusting ergometric
chair.
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OBJECTS OF THE INVENTION
It is an object of one embodiment of the present invention is to provide an
occupant-
weight-operated chair having a reclinable back wherein the chair is of a
simple economical
construction and lends itself to high production manufacturing and fabrication
procedures.
A further object is the provision of a tilting chair wherein the frame
supporting the seat
and back are pivotally connected to the seat and fixedly connected to the back
in a manner to
emphasize the isolated and separate appearance of the seat and back.
An alternative object is to provide armrests that are readily adjusted.
These and other objects and advantages of the invention will become apparent
as the
following description proceeds.
To the accomplishment of the foregoing and related ends, the invention, then,
comprises
the features hereinafter fully described and particularly pointed out in the
claims, the following
description and the annexed drawings setting forth in detail certain
illustrative embodiments of
the invention, these being indicative, however, of but a few of the various
ways in which the
principles of the invention may be employed.
SUMMARY OF THE INVENTION
Among advantages, some embodiments of the present invention provide an
occupant-
weight-operated chair having a reclining back wherein the occupant's weight
loads the chair
mechanism and automatically adjusts the reclining tension or force to recline
the chair back. In
a further preferred version of such embodiments, this occupant-weight-operated
chair provides a
substantially uniform force opposing the reclining of the chair back
throughout its range of
movement. Moreover, while this mechanism includes a spring, it does not rely
on a spring or
other adjustment to increase or decrease the chair reclining force. Instead,
the spring merely
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provides a secondary or auxiliary force to the force provided by the user's
weight. The spring
does not require any adjustment.
An occupant-weight-operated chair in accord with the inventive concepts
includes a chair
having a seat and a back mounted upon support structure, such as a caster-
mounted pedestal. The
back is reclinable with respect to the seat, and the structure of the chair,
and the relationship of
the components, is such that as the back is reclined the entire seat raises
against the weight of the
occupant. In this manner, the occupant's weight loads the chair mechanism, and
the force
required to recline the back is substantially uniform throughout the back-
reclining range of
movement, such force being regulated by the weight of the occupant upon the
seat rear portion.
In turn, through the connecting top links, lifts the entire seat a small
amount, typically between
about a quarter of an inch to an inch. Preferably, the seat is lifted by
between about a half and
three quarters of an inch.
Furthermore, the inventive occupant-weight-operated chair with a reclinable
back
attaches the back to the seat rear region so that reclining the back raises
the elevation of the seat
rear region against the occupant's weight. The combination of the upward
movement of the chair
seat in conjunction with the reclining rotation of the chair back simulates
the movement of the
user's torso about the user's hip joint as the user reclines.
Some other embodiments of the present invention provide a tilting chair
wherein the back
is theoretically pivoted relative to the seat at or in alignment with
approximately the ideal pivot
point of the body of a user (for reclining the back, the ideal pivot point
corresponds to a
horizontal axis through the user's hip joint). In addition, the seat lifting
is coordinated with the
back recline to simulate the natural action of the reclining body.
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In another embodiment, the present invention provides a chair occupant with a
headrest
support that adjusts to provide the support when support is needed and to
retract to an out of the
way position when not needed.
In still further embodiments of the present invention provides a chair
occupant with
armrests that readily, and simply adjust to deliver support to the user
through a greater range of
useful positions than was available through the arnirests that have been
heretofore available.
Such support should be provided when and as needed by the chair occupant.
A yet still further embodiment of this invention provides a variable
resistance to recline
of the back as the adjustable mechanism is tilted forward or rearward. In the
forward tilted mode
there is less resistance to recline and more resistance in the rearward tilted
mode. These changes
are effected automatically without adjustment being required by the user.
Some preferred embodiments of a tilting chair of the present invention have a
base that
pivotally supports a seat with opposite links of a two four-bar linkage
mechanisms. Typically, in
such embodiments, one set of the opposite links on each side of the chair
extends to support the
back. Additionally reclining chair embodiments of the present invention
usually have a base
that forms a fixed bar of the linkage. This linkage translates the actuation
of the rear links into a
change in the angle of the forward links.
Some of the reclining chairs of the present invention have a spring in the
base which acts
on one of the bars of the linkage is operative to urge the chair to an upright
position. This spring
also provides some assistance to counterbalance the user's recline force.
Desirably, the chair lift mechanism of a reclining chair of the present
invention is not
normally noticed by the user, nor does such a chair lift the user's feet off
of the floor.
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With the present invention, a tilting chair is provided wherein the seat back
pivot is
effectively at the ideal point and which obviates the problems of shirt tail
pull and feet lift
common in prior art chairs. The present invention provides a chair in which
both the seat and
back are supported from the base by a linkage mechanism which permits the
tilting of the back to
increase the angle of the user's torso to his legs.
This reclining of the seat and back can be achieved with a four-bar linkage.
The four-bar
linkage can be parallel or non-parallel. In one embodiment of the inventive
chair, the seat is
supported on each side by one of the links or cranks of the four-bar linkage.
The base of the
chair forms a second link, or crank. The third link, or crank, extends to
support the chair back.
The fourth link couples the forward portion of the base to the forward portion
of the seat.
The linkage is duplicated on each side of the chair.
The pivots of the linkage are designed so that the body weight tends to
balance the seat
pivot and a spring within the base is operative on one of the bars of the
linkage to urge the chair
to an upright position, simply to overcome the weight of the chair and
maintain an unoccupied
chair in an upright position.
Typically, when the chair is reclined by a user, the spring adds a small
amount of return
force. However, as the body weight of the user determines the amount of force
necessary to
return the chair to the upright position, and thus this force will vary among
users and the degree
of recline, the chair of the present invention uses the body weight of the
user to counter-act the
user's recline.
The bars of the linkage on each side of the chair are pivotally connected to
the seat and
the extended bar is fixedly connected to the back in a manner to emphasize the
isolated and
separate appearance of the seat and back.
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Typically, the base spaced below the seat is of relatively small clean and
compact
construction housing the lower journals for the above-noted third and fourth
links. In addition,
the base houses the spring and a vertical height adjustment mechanism.
The horizontal links above the base are rails on which the seat pan is
supported within
guide tracks so the seat may be slid back and forth to adjust seat depth. The
position of the seat
within the guide tracks is fixed by a conventional mechanism.
Preferably, the back and seat portions are formed of a molded, stiffly
flexible and
resilient, synthetic plastic material, such as a reinforced glass fiber or
other high strength material
capable of flexing. The seat includes an upper, underside, front, and rear
portions. Likewise, the
back has an upper, lower, front, and rear portions. The upper portion of the
seat and the front
portion of the back are typically contour molded and covered by a conventional
cushioning
material.
The underside of the seat front region (typically at the front of the rails
that support the
seat pan or support) is connected to the base by a pivot, and the underside of
the seat rear portion
is connected via a link to the lower region of the back.
As the seat reclines, and the rearward links (typically extensions of the back
support)
pivot about the rear pivot points on the chair base. As a result of the this
pivoting, the pivot
points under the seat support are raised slightly upwardly and rearwardly. The
action of the seat
support moving in this upward and rearward manner pulls the forward link
(e.g., the upper
horizontal seat support rails) so as to raise the forward portion of the seat.
This lifting of the seat
against the occupant's weight, accordingly, uses the occupant's weight to
"load" the back to resist
the reclining forces. As a result, a seat constructed in accordance with this
aspect of the
invention has a substantially uniform resistance to reclining due to the fact
that it is the
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occupant's weight which produces such resistance. As the reclining tension is
adjusted by the
weight of the occupant, the greater the occupant's weight, the greater the
force required to recline
the seat back, and vice versa.
In some embodiments of the present invention, the chair has one or two
adjustable
armrests. The adjustable armrests are supported by a pair of rods the
originate in the back of the
chair. Preferably, the adjustable arm support rods originate from an
"exoskeleton" that holds the
back of the chair. While it is most preferred that the chair having the
adjustable arms is the
reclinable chair of this application, the adjustable arms of the present
invention can be adapted to
most any chair having a back.
In a particularly preferred embodiment, the arms are readily raised or
lowered. To
disengage an arm, and permit it to be repositioned, the distal end of the
armrest is raised by a
slight amount, say about a centimeter. Once the positioning mechanism is
disengaged, the arm
can be readily repositioned to any height. When positioned, the arm is
released and it falls into
place, re-engaging the positioning mechanism. In one embodiment of this
adjustable arm
invention, a chair has two arms that are independent of each other. In an
alternative embodiment
of the adjustable arm invention, the movement of one arm adjusts the second
arm a
corresponding amount in the same direction.
In a particularly preferred embodiment, the chair has a headrest that moves
forward to
support the chair occupant's head as the chair is reclined back and retracts
as the chair returns to
its upright resting position. In this manner, the chair occupant's head is
supported when the
support is most needed, i.e., during full recline when the occupant's head is
not aligned with the
occupant's back. However, when the support is not needed, i.e., in the upright
position when the
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occupant's head is aligned with the occupant's back, the support is moved out
of the way. It is
preferred that the headrest moves on an arc that mimics the natural movement
of the head.
While it is most preferred that the chair having the automatically adjusting
headrest is the
reclinable chair of this application, the automatically adjusting headrest of
the present invention
can be adapted to most any chair having a reclinable back.
In yet another particularly preferred embodiment, an alternate support
mechanism may be
used in the base or lower link position that allows the entire chair above the
base to be tilted
forward or to the rear and locked in any position, i. e., either extreme or at
any position between
these extremes. This alternate support mechanism provides forward tilt for
seat and back for
work positions, such as writing, and the rearward tilt provides additional
recline to the backrest.
From time to time, the term "resting position" is used herein to refer to the
upright or
forward tilt position of the unoccupied chair.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a side elevation of a reclining chair in accordance with the present
invention
illustrating the seat and back in upright position;
FIG. 2 is a side elevation of a reclining chair in accordance with the present
invention
illustrating the seat and back in tilted position;
FIG. 3 is a side elevation of a reclining chair having the automatically
adjusting headrest
and adjustable armrests in accordance with the present invention illustrating
the seat and back in
upright position;
FIG. 4 is a side elevation of a reclining chair having the automatically
adjusting headrest
and adjustable armrests in accordance with the present invention illustrating
the seat and back in
tilted position;
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FIG. 5 is a side elevation of a reclining chair having the increased tilt
mechanism in
accordance with the present invention illustrating the seat and back in
upright position;
FIG. 6 is a side elevation of a reclining chair having the increased tilt
mechanism in
accordance with the present invention illustrating the seat and back in tilted
position;
FIG. 7 is a side elevation view of a chair base useful with the chair of the
present
invention;
FIG. 8 is a side elevation view of a chair base capable of providing extra
tilt to a chair of
the present invention in the resting position;
FIG. 8A is an exploded side elevation view of the chair base of FIG. 8;
FIG. 9 is a side elevation view of a chair base capable of providing extra
tilt to a chair of
the present invention in the increased tilt position;
FIG. 10 shows a top view of an embodiment of a chair base of the present
invention;
FIG. 11 shows a side view of a preferred armrest including locking mechanism
with the
locking mechanism engaged;
FIG. 12 shows a side view of a preferred armrest including locking mechanism
with the
locking mechanism disengaged;
FIG. 13 shows a side view of an alternative armrest locking mechanism with the
locking
mechanism engaged;
FIG. 14 shows a side view of an alternative armrest locking mechanism with the
locking
mechanism disengaged;
FIG. 15 shows a side view of a further alternative armrest locking mechanism
with the
locking mechanism engaged;
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FIG. 16 shows a side view of a further alternative armrest locking mechanism
with the
locking mechanism disengaged;
FIG. 17 shows an isometric side view of two interconnected armrest mechanisms;
FIG. 18 shows an isometric side view of two isolated armrest mechanisms;
FIG. 19 shows an isometric side view of two armrest mechanisms interconnected
via the
top support arm;
FIG. 19A is a cutaway view along line 19A-19A showing the armrest locking
mechanism;
FIG. 19B shows an exploded view of an armrest locking mechanism;
FIG. 20 shows a side view of a headrest mechanism of the present invention;
FIG. 20A shows a cut away view of the headrest mechanism of FIG 20 taken along
line
20A-20A;
FIG. 20B shows a cut away view of the headrest mechanism of FIG 20 taken along
line
20B-20B;
FIG. 20C shows a cut away view of the headrest mechanism of FIG 20 taken along
line
20C-20C;
FIG. 21 shows a view of an embodiment of a mechanism according to the present
invention for couplingly using the chair occupant's weight to counteract the
reclining of the chair
back in isolation;
FIG. 21 shows an exploded view of a means for movably mounting a seat on the
seat
support in an embodiment of the present invention;
FIG. 22 shows a view of an exploded view of an automatically adjustable
headrest;
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FIG. 23 is a side cutaway view showing an embodiment of a supplemental
backrest
adjustment mechanism;
FIG. 23A is an exploded view of the embodiment of FIG. 23;
FIG. 24 is a top view of an embodiment of a chair having a pivotable armrest
development;
FIG. 25 is a top view of a pivotable armrest with the armrest cushion removed;
FIG. 26 is a side view of a pivotable armrest;
FIG. 27 is a rear view of a pivotable armrest;
FIG. 28 is a sectional view of a pivotable armrest taken along line 28-28 in
FIG 26;
FIG. 29 is a sectional view of a pivotable armrest taken along line 29-29 in
FIG 26;
FIG. 30 is a sectional view of a pivotable armrest taken along line 30-30 in
FIG 26;
FIG. 31 is a sectional view of a pivotable armrest taken along line 31-31 in
FIG 26;
FIG. 32 is a sectional view of a pivotable armrest taken along line 32-32 in
FIG 26;
FIG. 33 is a sectional view of a pivotable armrest taken along line 33-33 in
FIG 26;
FIG. 34 is a side view of a preferred embodiment of the inventive chair
incorporating the
inventive armrest and the inventive headrest;
FIG. 34A is a sectional view of the back of the chair of FIG. 34 taken along
line 34A-34A
in FIG. 34; and
FIG. 34B is a sectional view of the back of the chair of FIG. 34 taken along
line 34B-34B
in FIG. 34.
DETAILED DESCRIPTION
The present invention comprises several developments that can be incorporated
singly, or
in any combination, into conventional chair designs. For example, the method
and mechanism of
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the present invention for reclining the back of a chair can be used alone, or
it could be used with
the method and mechanism of the adjustable armrest, the method and mechanism
of the
adjustable headrest and/or the method and mechanism of the tilt mechanism.
FIG. 34 illustrates
a chair that incorporates several aspects of the present invention into a
chair design specifically
including the method and mechanism of the present invention for reclining the
back of a chair,
the method and mechanism of the adjustable armrest, the method and mechanism
of the
adjustable headrest and the method and mechanism of the tilt mechanism.
To understand how the present invention operates, the several separate
inventive aspects
are described separately. To start with, the method and mechanism for
reclining the back of the
seat in a way that uses the seat occupant's weight to counteract the reclining
force is described.
Thereafter, other inventive aspects of the inventive chair design are
described.
Referring first to FIG. 1, it will be seen that the chair comprises a base
110, a seat 111
which is secured to seat support 119 and a back support 113 which supports
back 112. The base
110 is supported on pintle 114 projecting upwardly from the center of five-
legged pedestal 115,
the ends of the legs accommodating casters 116 supporting the chair on floor
117.
Seat 111 is supported by seat support 119, which in turn is connected to base
110
rearwardly by back support extension 123 and forwardly by support arm 120.
Specifically, back
support extension 123 is connected to base 110 by horizontal pivot point 124
and to seat support
119 by horizontal pivot point 122. Correspondingly, support arm 120 is
connected to base 110
by horizontal pivot point 121 and to seat support 119 by horizontal pivot
point 118. As a result,
the combination of base 110, support arm 120, seat support 119, back support
extension 123 and
horizontal pivot points 118, 121, 122 and 124 form a substantially
parallelogram linkage that
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permits movement between the forward and downward position in one direction
(shown in FIG.
1) and the rearward and upward position of seat 111 in the other direction
(shown in FIG. 2).
An imaginary horizontal extension of base 110 and support arm 120 forms a
forward
facing acute angle 101, which, when the chair is in its resting position, is
of at least about 5 ,
preferably of at least about 10 , and most preferably of at least about 20 .
Nonetheless, the
forward facing acute angle 101, when the chair is in its resting position, is
normally less than
about 45 and preferably less than about 40 . A highly preferred forward
facing acute angle
101, when the chair is in its resting position, is about 26 .
Correspondingly, base 110 and back support extension 123 form a forward facing
acute
angle 102 which is typically less than the forward facing acute angle 101. The
forward facing
acute angle 102, when the chair is in its resting position, is of at least
about 5 , preferably of at
least about 8 , and most preferably of at least about 15 . Nonetheless, the
forward facing acute
angle 102, when the chair is in its resting position, is normally less than
about 40 and preferably
less than about 30 . A highly preferred forward facing acute angle 102, when
the chair is in its
resting position, is about 18 .
It is preferred that the raising of seat 111 to counteract the reclining of
back support 113
lifts seat 111 between about 0.2 and 2 inches. Its is further preferred that
the seat is raised
between about 0.4 and 1 inch. In a particularly useful embodiment of the
present reclining chair
invention, the seat is raised by about 0.6 inches in the front and by about
0.8 inches in the rear.
As is apparent from the above description, the pivot point for the recline of
the back
support 124 is not the chair occupant's hip joint. Consequently, the recline
of the back
circumscribes an arc that is displaced from the arc based on the user's hip
joint. However, the
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concurrent action of the reclining mechanism described herein of raising the
seat produces a net
positioning of the user that is substantially the same as the positioning
which would have been
achieved if the center of the back recline arc were coextensive with the hip
joint.
FIGs. 1 and 2 also show spring means 125 which acts to restore back support
113 to its
resting position when the chair is unoccupied.
Typically, both seat 111 and back 112 have a rigid shell, such as an injection
molded
plastic. It is preferred that seat I 11 has a layer of a non-compressible,
displacing gel. For
example, a polyurethane gel is useful. Typically the gel pad on seat 111 is
about half an inch
thick and is located on top of a one inch thick layer of a conventional soft
foam. It is further
preferred that the seat 1 I 1 is shaped to reduce pressure points at the
thickest portion of the gel.
Typically the back 112 has an about'/4 inch thick layer of a conventional soft
foam
attached to the rigid shell.
FIG. 21 provides another view of the interaction of the parts of the mechanism
that uses
the chair occupant's weight to counteract the reclining forces to help return
the chair back to its
upright or resting position. Again, chair back 113 is pivotally linked to base
110 at pivot point
124. Chair back extension 123 continues and is pivotally linked to seat
support 119 at pivot
point 122. Similarly, the front of base 110 is linked to the front of seat
support 119 by the
operation of link 120 which is pivotally coupled to base 110 at pivot point
118 and it is pivotally
connected to seat support 119 at pivot point 121.
FIG. 21 also shows spring 125 and telescoping spring guide 464 interacting
through
pillow block 715 with connecting element 350, which is attached to back
support arms 113.
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Also shown in FIG. 21 is a plurality of slots that permit the seat of the
chair to be
advanced forward or backward to alter the chair to better accommodate a user.
In the
embodiment shown in this figure, the slots anchor the seat in the appropriate
position.
FIG. 21A shows a means to secure the movable seat in the desired position. In
this
embodiment, lifting lever 2100 causes lever 2100 to pivot about pivot joint
2110 and lift pin
2120 out of slot 2130. When pin 2120 is out of slot 2130, seat 111 can move
along support 119,
while being attached by pin 2140 that has an enlarged head 2145 below support
119. At its
upper end, pin 2140 is attached to seat I 11.
An alternative mechanism for interconnecting the seat occupant's weight to the
force to
restore the chair to its upright position replaces support arm 120 with a
mechanism that performs
the same function as the four-bar mechanism described above can be substituted
for the four-bar
mechanism. For instance, support arm 120 could be replaced by a track mounted
on base 110
and a traveler projecting downward from seat support 119. When back support
extension 123 is
pivoted as back 112 is reclined, seat support 119 pulls the traveler up the
track which is inclined
in a backward direction. Desirably, the track or the traveler, or both, have a
low friction surface
such as polytetrafluoroethylene.
In the embodiments of the present invention having a headrest, it is preferred
that the
headrest has a layer of about one inch thick of a conventional soft foam.
A first embodiment of base 110 of the present invention is illustrated in FIG.
7. As seen
in this figure, base 110 is mounted on pintle 114 via piston 400. Piston 400
is part of a
conventional gas cylinder for raising or lowering the height of the chair.
Base 110 has a forward
pivot axis 121 and a rearward pivot axis 124. In the reclining chair of the
present invention, the
pivot axes are connected to two links of the four-bar linkage that
interconnects the reclining of
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the chair back with a raising of the seat. Base 110 also has a spring means
125 that applies a
force to the chair so as to maintain the unoccupied chair in its upright
position. Spring means
125 is mounted about cylinder 720, which in turn is mounted on cylinder base
710 which is
attached, preferably pivotably attached, to attachment point 700 which is an
integral portion of
base 110.
Additionally, FIG. 7 also shows telescoping spring guide 464 (which is
slidably mounted
in spring cylinder 720). Pivotably seated on top of telescoping spring guide
464 is a top pillow
block 715 which bears against connecting element 350 between back support arms
113.
Desirably, the top pillow block 715 is made of a low friction material such as
polytetrafluoroethylene commonly marketed under the Tradename TEFLON.
Also shown in FIG. 7 is extension 725, attached to seat support or link 119,
which in
automatically adjusting headrest embodiments can form an attachment platform
for the rod that
translates the recline of the chair back into a forward motion of the
headrest.
In an alternative, preferred embodiment of the present invention, for purposes
of tilting
seat 111 and back 112, base 110 has a somewhat inclined, two-part housing. For
instance, as
shown in FIGs. 8 and 10, top 320 of base 110 houses horizontal pivot points
121 and 124. Also
shown in FIG. 10 is housing 315 for a conventional mechanism (such as lever
317) for releasing
a first conventional gas cylinder located in pintle 114 that controls the
elevation of base 110.
This embodiment also has a second conventional gas cylinder, namely gas
cylinder 300. Gas
cylinder 300 functions to tilt the portions of the chair above base 110 and
all parts attached to top
320.
FIG. 8 shows a side view of base 110 in the forward tilted position. In this
view, base
housing top 320 is substantially horizontal. Base housing top 320 is pivotally
connected to base
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housing bottom 430 at horizontal pivot point 121. Piston 420 of gas cylinder
300, is pivotally
connected to linkage 430 at pivot point 431. In turn, linkage 430 is pivotally
connected to
linkage 433 at pivot point 432, forming a crank, which is connected at pivot
point 435 to linkage
437 which is secured to base housing top 320 at pivot point 439. Through this
linkage system,
gas cylinder 300 applies a force to alter the tilting angle of the chair parts
above it.
Also shown in FIG. 8 is a conventional linkage mechanism that operatively
connects
housing 315 (for lever 317) with a conventional release mechanism 405 for
conventional gas
cylinder 400 located in pintle 114 that controls the elevation of base I 10.
In a preferred embodiment of the mechanism of FIG. 8, the counterclockwise
rotation of
lever 317 activates conventional release mechanism 405, whereas the clockwise
rotation of lever
317 activates gas cylinder 300. Concurrently, the clockwise rotation of lever
317, because of slot
427, permits the mechanism connecting lever 317 to gas cylinder 400 to "float"
or slid in slot
427 and thereby not activate conventional release mechanism 405
FIG. 8 further shows the preferred spring mechanism that increases the tilt
restoring force
as the tilt angle is increased. Specifically, spring 125 is mounted on spring
base 460 that is
pivotally connected to mount 458 within chamber 456 of spring housing 450. Arm
454 pivotally
connects spring housing 450 to lower base housing part 408. Mounted in spring
125 is spring
piston 462, the top of which, spring piston top (or telescoping spring guide)
464, pushes against
chamber 468 top 466.
It is preferred that chamber 468 top 466 is an arc equidistant from spring
base 460 mount
458 to chamber 468 top 466. This arrangement allows spring 125 and piston
assembly (or
telescoping spring guide) 464 to move varying distances from pivot 124,
thereby increasing or
reducing leverage force to back support 113.
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FIG. 9 shows a side view of base 110 in its full rearward tilt position. In
this view, base
housing top 320 is substantially inclined. In particular, arm 454 and its
pivotal connection 452,
in this figure, has slid radially along the under-surface of top 466 to its
position furthest from the
pivot axis at 124. Top 466 has an under-surface which is angled in a
curvilinear fashion such
that arm 454 connected to spring base 460, spring piston 462 and piston
assembly (or telescoping
spring guide) 464 is tilted to the rear moving the top of spring 125 further
from pivot 124 thereby
increasing leverage. The top of telescoping spring guide 464 is pivotally
seated in pillow block
715 so that it will slide along the arcuate under-surface of top 466 without
changing compression
of spring 125. As a result of this repositioning, spring piston top 464 now
pushes against
chamber 468 top 466 at a point that is further from horizontal pivot point
124. In other words, as
the tilt mechanism increases is rearward tilt, the centerline of spring 125
tilts rearwardly at an
increased angle relative to a vertical plane. These changes increase the
leverage on spring 125 in
the rear tilted position, producing a recline compression in spring 125 that
increases as the angle
of the tilt of spring 125 from the vertical plane increases and decreases as
the angle of the tilt of
spring 125 from the vertical plane decreases. The net effect is to increase
the resistance of
spring 125 to any further incremental deformation. This increase in spring
125's resistance to
incremental deformation provides greater resistance to support the increased
load on the backrest
resulting from the occupant being at a greater recline angle with more load of
the occupant's
upper body transferred to the back rest.
Spring 125's resistance to incremental deformation can be increased as the
chair is
reclined in other ways. For example, any mechanism that tilts spring 125 away
from horizontal
pivot point 124 could accomplish this end. In an alternative embodiment,
spring 125 is mounted
on a pivoting base from which arises a shield. A manually engaged bar pushes
against the shield
WO 00/74531 CA 02394954 2002-06-18 PCT/US00/15327
and thereby tilts spring 125. This tilting increases the distance between the
top of spring 125 and
horizontal pivot point 124, which increases spring 125's resistance to
incremental deformation.
The functioning of the additional tilt mechanism of the present invention
incorporated
into a reclining chair is illustrated in FIGs. 5 and 6. FIG. 5 shows the chair
in a resting position.
Not shown in the FIGs. is a forward tilt position that the additional tilt
mechanism is able to
achieve. FIG. 6 shows a reclining chair with the additional tilt mechanism in
an enhanced tilt
position.
More particularly, in FIG. 5, top 320 of base 110 is in a somewhat horizontal
position.
As top 320 is the fixed link in the four-bar linkage that raises seat 111,
when top 320 is
horizontal, seat 111 is also largely horizontal. Lower base housing part 408
is pivotally
connected to top 320 of base 110 at pivot point 121. When the chair occupant
reclines in the
chair, the additional tilt mechanism lowers the rear portion of top 320 while
the forward portion
of top 320 remains in substantially the same position. This movement of top
320 moves 454
about pivot 452, which in turn lowers spring housing 450 and increases the
angle between the
centerline of spring 125 and a vertical line going through the base of the
centerline of spring 125.
This movement also increases the distance between pivot point 124 and the
point at which spring
350 contacts back support 113.
As noted above, this rotation of spring 125 increases the distance of the
center of spring
pressure which in turn increases the force urging the chair back into its
resting position.
However, this spring force requires the additional force provided by the
occupant's weight to
return the chair to the upright position when the chair occupant reclines.
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Desirably, the additional tilt mechanism adds up to between about 1 and 15
of a
forward tilt (i.e., a tilt in which the rear end of the seat rises in relation
to the front) and it is more
preferred that the additional tilt mechanism adds up to between about 3 and
10 of a forward tilt.
It is yet further preferred that the additional tilt mechanism adds up to
between about 4 and 8 of
forward tilt. In a particularly preferred embodiment, the additional tilt
mechanism adds up to
about 6 of a forward tilt.
As noted above, the additional tilt mechanism add up to between about 1 and
12 of a
rearward tilt (i.e., a tilt in which the rear end of the seat is lowered in
relation to the front). It is
more preferred that the additional tilt mechanism adds up to between about 2
and 10 of a
rearward tilt. It is yet further preferred that the additional tilt mechanism
adds up to between
about 3 and 7 of rearward tilt. In a particularly preferred embodiment, the
additional tilt
mechanism adds up to about 5 of a rearward tilt. In adding an additional
rearward tilt, caution
must be taken to prevent the chair from reclining to a position such that the
center of gravity of
the occupied chair is moved significantly behind pintle 114 to prevent the
chair from tumbling
over backwards.
In a further aspect of the present invention, the chair is provided with a
headrest that is
urged forward as the back of the chair is tilted. The more the chair is
tilted, the more the headrest
moves forward. A preferred embodiment of this automatic headrest adjustment
mechanism in a
chair that incorporates both the reclining back that is opposed by the weight
of the user and the
automatically adjusting headrest developments of the present invention is
illustrated by FIGs. 3
and 4.
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Specifically, in addition to the several elements discussed in connection with
the reclining
mechanism of the chair of FIG. 1, this embodiment also includes automatically
adjusting
headrest 370.
Mounted to the back of headrest 370 (also illustrated in an enlarged form in
FIG. 20) is
vertical adjustment bar 380. Typically, there are a pair of parallel vertical
adjustment bars 380
mounted to the back of headrest 370. It is preferred that vertical adjustment
bars have an
adjustment range of between about 2 and 10 inches, and it is more preferred
that these bars have
an adjustment range of between about 3 and 7 inches in length. A particularly
preferred range of
vertical adjustment bar is about 5 inches.
Vertical adjustment bar(s) 380 pass through mounting 390. It is preferred that
mounting
390 and vertical adjustment bar 380 interact in a manner that retains the
position of the headrest
370 relative to mounting 390. For example, vertical adaustment bar 380 might
be maintained in
position within mounting 390 by a conventional frictional engagement.
Alternatively, vertical
adjustment bar 380 might have a plurality of apertures through which a
mounting bar might pass
to anchor vertical adjustment bar 380 within mounting 390. A further
alternative might consist
of a conventional ratchet mechanism or substantially any other conventional
means for fixing the
position of a bar within a mounting.
Mounting 390 is affixed to a carriage 385. Carriage 385 travels along a track
on the
interior side of back support extension 375. Back support extension 375, and
correspondingly
the track along the interior side of back support 375, is curved. The curve of
back support
extension 375 (and hence of the interior track) corresponds to the arc through
which a user's
head travels when it the head is tilted back and forth when the user is
seated. Desirably, this arc
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has a centerpoint corresponding to an imaginary axis through the shoulder
joint of the user and a
radius corresponding to the distance from this centerpoint to the bottom of
the user's ear.
At carriage connection 365, carriage 385 is pivotally connected to rod 360 at
point 367.
Rod 360 is at its lower end, pivotally connected to seat support extension 725
at point 357, which
in turn is connected to seat support 119. As the length of rod 360 is
substantially fixed, the
differential in arc between chair back 113 and lower rod pivot 725 combined
with the additional
lifting action of seat support 119 to which pivot 725 is a part results in an
upward push on rod
360 which in turn moves head rest support carriage 385 in its track 375 to
cause the desired
upward and forward motion. This upward force causes carriage 385 to travel
along the track
that is on the interior side of back support 375 in an arcuate path. This
movement of carriage 385
in turn, moves headrest from its position substantially aligned with back
support 113 to a forward
position shown in FIG. 4. As a result of this motion, headrest 370 is
positioned by the reclining
of the chair into the position where it provides the head of the chair user
the support needed when
the user reclines.
Cut away view FIG. 20A shows a spring and piston mechanism that can be used to
hold
vertical adjustment bar(s) 380 in place in mounting 390.
Cut away view FIG. 20B shows how tongue 387 of carriage 385 fits into track
groove
377 of back support extension 375.
Cut away view FIG. 20C shows how back support extension 375 is secured to back
113
by a conventional attachment means such as a screw.
FIGs. 20 and 22 provide alternative views of an embodiment of an automatically
adjusting headrest according to the present invention. Upper and lower
interior portions of
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headrest 370 are connected by vertical adjustment bars 380. Vertical
adjustment bars pass
through mounting 390 as described above.
Mounting 390 is affixed to the upper portion of carriage 385. Near the lower
portion, rod
360 is connected to carriage at point 365.
Carriage 385 travels along a track in back support extension 375 and is
propelled by a
force applied to carriage 385 by rod 360.
Exploded view FIG. 22 shows an embodiment of the track in back support 375
along
which carriage 385 travels. In this embodiment, the track is groove 377 which
is in the interior
side of each back support 375. Complementarily, carriage 385 has a tongue 387
on each exterior
side adapted to fit within grooves 377.
Yet another aspect of the present invention is a mechanism for fixing the
position of the
adjustable arms which can be used in any chair, including the reclining chair
of the present
invention. FIGs. 11 and 12 illustrate a preferred embodiment of the mechanism
for fixing the
position of the adjustable arms. In FIG. 11, the mechanism is engaged and the
arm is secured in
its position. The same mechanism is shown in FIG. 12 where the mechanism is
disengaged and
the position of the arm can be readily changed.
More particularly, FIG. I 1 shows armrest 600 in an in use (and locked)
position. Armrest
600 is attached by a pair of pivot joints 615 and 620 to corresponding
substantially parallel bars
625 and 630. These bars 625 and 630 are connected to back 113. In this
embodiment, back 113
has at least two ratchet surfaces 640 and 650 located on opposite sides of the
interior of back
113. Secured to bar 625 by a connecting device 660 is locking bar 675 which
has a ratchet face
that is complementary to ratchet tooth 640. Similarly, secured to bar 630 by a
connecting device
665 is locking bar 670 which has a ratchet face that is complementary to
ratchet tooth 650.
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When terminal end 610 of aimrest 600 is gently raised, as shown in FIG. 12,
bar 625 is
pushed backward while concurrently bar 630 is pulled forward. This movement of
bars 625 and
630 correspondingly cause complementary ratchet face 645 to disengage from
ratchet tooth 640
and complementary ratchet face 655 to disengage from ratchet tooth 650. In
this disengaged
condition, the armrests can be repositioned with very little effort.
To assist the engagement of the ratchet faces with the complementary ratchet
teeth, the
reverse side of the locking bars (670 and 675) can have a chamber into which a
spring 34 can
push against a piston 690 that in turn pushes against an interior wall of a
chamber inside back
support arms 113 to drive the ratchet teeth into the complementary ratchet
faces.
Typically, the armrests are attached to the back of the chair about 6 to 12
inches above
the rear portion of the seat.
Commonly when a chair has two armrests that are coupled together, the two
armrests are
linked by a pair of substantially "C" shaped rods. The locking mechanism
interacts with these
substantially "C" shaped rods at the points where the rods pass through the
support for the chair's
back, or a housing for this purpose mounted on the back of the chair. When the
arms are not
interconnected, the shape of the rods may be approximately quarter circle
shaped. However,
these shapes are general characterizations, any shape can be used provided the
shape is effective
to (i) position the two armrests substantially parallel to the sides of the
seat (if the armrests
incorporate the horizontal adjustment development of the present invention,
then the armrests
should be substantially parallel to the sides of the seat when the armrests
are in a centered
position) and (ii) not interfere with the user sitting back in the chair.
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U.S. Patent No. 5,292,097 to Russell discloses a variety of alternative
locking
mechanisms that can readily be adapted for use in support of the armrest of
the present invention.
This patent is hereby incorporated by reference.
FIGs. 13 and 14 illustrate an alternative embodiment of the mechanism for
fixing the
position of the adjustable arms. In this embodiment, only lower bar 630 has a
ratchet
face which engages with a ratchet tooth 650. Correspondingly, FIGs. 15 and 16
illustrate a
further embodiment of the mechanism for fixing the position of the adjustable
arms in which
only upper bar 625 is connected to a ratchet face 645 that engages a ratchet
tooth 640.
In a preferred embodiment of the mechanism for fixing the position of the
adjustable
arms, for a chair having a left and a right arm, the two arms are
interconnected so that the
adjustment of one arm adjusts the other. In such an embodiment, a preferred
configuration is one
in which only upper bar 625 on one arm, e.g., the right arm, has a ratchet
face 645 and a
corresponding ratchet tooth 640 and on the other are, the left arm in this
example, only the lower
bar 630 has a ratchet face 655 and a ratchet tooth 650. In such embodiments,
there are two
ratchet mechanisms (one on an upper bar and one on a lower bar) between the
two arms that
cooperate to control the positioning of the arms.
FIG. 17 provides an isometric view of a pair of armrests in which the upper
and the lower
bars are interconnected. Specifically, armrests 600 are supported by upper
bars 625 and lower
bars 630. Within back supports 113, the upper bars 625 and lower bars 630
engage and
disengage with the positioning mechanisms. Upper bars 625 are interconnected
by connecting
bar 637 and lower bars 630 are interconnected by connecting bar 633.
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FIG. 18 provides an isometric view of a pair of armrests in which the upper
and lower
bars are independent. In this embodiment, the repositioning of one arm does
not effect the
position of the other.
FIG. 19 provides an isometric view of a pair of armrests in which upper bars
625 are
interconnected. In this embodiment, the repositioning of one arm is translated
into the
repositioning of the other arm by means of connecting bar 637.
In an alternative embodiment, connecting bar 637 may include a conventional
means to
connect and disconnect the bar, such as a sliding bar or a set screw. In such
an embodiment, the
user can choose to have the adjustment of one armrest adjust the other when
the connecting bar is
used or the adjustment of one armrest becomes independent of the other when
the connecting bar
is disengaged.
FIG. 23 shows yet a still further aspect of the present invention that can be
incorporated
into the reclining chair of the present invention or any other chair having a
back support 113 and
a separate seat back 112. In this embodiment, a track 900 mounted on the
forward side of back
support 113. Seat back 112 has a pair of carriages adapted to travel on these
tracks 900. In
addition, either track 900 or carriage 910 has a conventional locking
mechanism for fixing the
position of carriage 910 on track 900.
Useful conventional locking mechanisms include ratchet mechanisms, levers that
cause
the carriage 910 to clamp onto track 900, screw mechanisms, and mechanisms in
which a pin is
inserted to fix the carriage position.
In a particularly preferred embodiment of the track 900 and carriage 910
mechanism,
carriage 910 also has a conventional pivot mechanism that permits seat back
112 to rotate
somewhat about this pivot and provide a further adjustment to better support
the chair occupant.
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Such an embodiment is illustrated in FIG. 23A. To fix carriage 910 into the
appropriate position,
lever 920 is attached to carriage 910. Mounted on lever 920 is pin 930 which
when engaged fits
into one of a plurality of slots 940. Conversely, when lever 920 is pulled and
pin 930 is
withdrawn from slot 940, carriage 910 can be moved up or down along track 900
and then when
lever 920 is retumed to its engagement position, pin 930 enters a new slot 940
and secures seat
back 112 into position. A spring can be employed to urge lever 920 into
engagement.
Additionally, seat 111, or alternatively a conventional seat pan located
directly under seat
111, can be mounted on a pair of carriages that are adapted to travel along a
track mounted on the
top of seat supports 119. Desirably such carriages would also have a
conventional means for
fixing the position of the carriages on the track. Additionally, it is also
desirable that such tracks
have stops on each end of the track to prevent the carriage from traveling
beyond the end of the
tracks. By putting seat 111 on such a track mechanism, the user is provided
with yet another
means of ensuring that the seat conforms the geometry of the user's body, and
not vice versa.
A further development in armrests that can be incorporated into the adjustable
armrests of the present invention, or into conventional armrests is a
mechanism to permit pivotal
horizontal repositioning of the armrests As illustrated in FIGs. 24 through
33. For instance, as
shown in FIG. 24, armrest 600 can be pivoted either inward or outward. This
additional
pivoting of the armrest allows the user to position the armrest under the
user's forearm when the
user is performing a task such as typing on a keyboard. As a result, the chair
provides more
support to the user and as a result, it is believed that the user will be less
worn as a result of using
such support.
Turning now to FIG. 25, a top 800 view of an embodiment of a pivoting armrest
taken
without the cushioning. Starting at the back of armrest 600, there is clevis
base 810 which
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attaches to bars 625 and 630 to support armrest 600. Within clevis base 810
there is a pivot pin
that permits the rotation of armrest 600 about pin 805. However, to restrict
the range of rotation
available in armrest 600, attached to pivot pin 805 is index arm 820 whose
motion is restricted
by index arm limiters 815. Additionally, to prevent free pivoting of armrest
600, the armrest also
has bar 825 with grooves into which index bar 820 can be secured.
, In the embodiment of FIG. 25, bar 825 is locked into place (or permitted to
swing freely)
by the cooperative action of spring 830, cam follower 840, cam cut-out 845 and
sliding lock-
release control 835. When sliding lock-release control 835 is in the position
shown, spring 830
urges bar 825 towards index arm 820 so as to lock pivoting armrest 600 in
place. However,
when sliding lock-release control is slid into its alternate position, cam
follower 840 is positioned
in its alternate position in cam cut-out 845, which releases the tension of
spring 830 on bar 825
and thereby permitting index arm 820 to be moved into.a different groove. If
cam follower 840
is left in the detent position, lock bar 825 is disengaged so that armrest 600
can move freely.
In a further preferred embodiment of the pivoting armrest, the distance
between adjacent
grooves represents about 5 of pivoting. Thus, if there are six grooves,
armrest 600 can be
pivoted through about 30 of pivoting.
FIG. 26 shows a side view of a pivoting armrest embodiment. In this view,
armrest 600
is attached to bars 625 and 630 by conventional fastening means 615 and 620,
respectively.
Useful fastening means include nuts and bolts, and clevis pins.
Also in this view clevis base 810 is seen as is pivot pin 805. Additionally,
index arm
limiter 815 is seen in the plane of index arm 820. Spring 830 urges bar 825
into index arm 820.
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Sliding lock-release control 835 projects out slightly from armrest 600.
Screws 850 attach the
cushioning top to the armrest body.
It is particularly preferred that the sliding lock-release control 835 is
positioned under the
interior tip of the user's thumb on one side and the user's fingers on the
other so that the user can
readily adjust the pivot position of the armrest.
FIG. 27 shows a rear view of a pivoting armrest. In this view, clevis base 810
and sliding
lock-release controller 835 are apparent.
FIG. 28 shows a sectional view of armrest 600 taken along line 28-28 in FIG.
26. In this
view, both the locked and released positions of sliding lock-release control
835 can be seen.
FIG. 29 shows a sectional view of armrest 600 taken along line 29-29 in FIG.
26.
FIG. 30 shows a sectional view of armrest 600 taken along line 30-30 in FIG.
26.
FIG. 31 shows a sectional view of armrest 600 taken along line 31-31 in FIG.
26.
FIG. 32 shows a sectional view of armrest 600 taken along line 32-32 in FIG.
26.
FIG. 33 shows a sectional view of armrest 600 taken along line 33-33 in FIG.
26.
31
