U.S. patent application number 09/833492 was filed with the patent office on 2001-11-15 for chair.
Invention is credited to Caruso, Jerome C., Caruso, Steven J., Gezon, Bruce R., Gierz, Marc A., Nyenhuis, Jack R..
Application Number | 20010040399 09/833492 |
Document ID | / |
Family ID | 26753012 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010040399 |
Kind Code |
A1 |
Caruso, Jerome C. ; et
al. |
November 15, 2001 |
Chair
Abstract
A tiltable chair including a housing, a back support pivotally
attached to the housing about a first horizontal axis and a seat
support pivotally attached to the housing about a second horizontal
axis. A leaf spring includes a first end engaging the housing and a
second end biasing the back support and seat support in an upward
direction. A fulcrum member is moveably supported in the housing
and engages a bottom surface of the spring intermediate the first
and second ends of the spring. The chair also include an adjustable
backrest and armrests slideably mounted on the back support, and a
seat slideably mounted on the seat support. A tilt limiter is
provided to limit the rearward tilting of the chair. A selector
member includes indicia that indicates the setting of the tilt
limiter so as to apprise the user of maximum available rearward
tilt position of the chair.
Inventors: |
Caruso, Jerome C.; (Lake
Forest, IL) ; Caruso, Steven J.; (Antioch, IL)
; Gezon, Bruce R.; (Caledonia, MI) ; Gierz, Marc
A.; (Hudsonville, MI) ; Nyenhuis, Jack R.;
(Jenison, MI) |
Correspondence
Address: |
BRINKS HOFER GILSON & LIONE
P.O. BOX 10395
CHICAGO
IL
60610
US
|
Family ID: |
26753012 |
Appl. No.: |
09/833492 |
Filed: |
April 11, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09833492 |
Apr 11, 2001 |
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09234291 |
Jan 20, 1999 |
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6250715 |
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60072111 |
Jan 21, 1998 |
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60078938 |
Mar 20, 1998 |
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Current U.S.
Class: |
297/300.2 ;
297/302.1 |
Current CPC
Class: |
A47C 1/03277 20130101;
A47C 1/03255 20130101; A47C 7/402 20130101; A47C 1/03294 20130101;
A47C 1/03238 20130101; A47C 1/03266 20130101; A47C 1/03 20130101;
A47C 1/0303 20180801 |
Class at
Publication: |
297/300.2 ;
297/302.1 |
International
Class: |
A47C 001/032 |
Claims
What is claimed is:
1. A chair comprising: a housing; a back support pivotally
connected to said housing about a first horizontal axis; a seat
support pivotally connected to said housing about a second
horizontal axis; at least one leaf spring comprising a first end
engaging said housing and a second end biasing said back support
and said seat support in an upward direction; and a fulcrum member
moveably supported by said housing and engaging said at least one
leaf spring between said first and second ends; whereby said
fulcrum member can be moved so as to engage said at least one leaf
spring at various points intermediate said first and second ends
and thereby alter the amount of resistance applied to said back
support and said seat support as a user tilts rearwardly on the
chair.
2. The chair of claim 1 wherein said seat support is slidably
connected to said housing at said second horizontal axis
3. The chair of claim 1 wherein said housing comprises a forward
portion and said at least one leaf spring engages said forward
portion
4. The chair of claim 1 further wherein said seat support is
pivotally connected to said back support about a third horizontal
axis
5. The chair of claim 4 further comprising a pivot member pivotally
connecting said back support and said seat support at said third
horizontal axis, wherein said second end of said at least one leaf
spring engages said pivot member to bias said back support and said
seat support in an upward direction
6. The chair of claim 1 further comprising a pivot member mounted
to said housing and defining said second horizontal axis and
wherein said seat support has a slot, said housing pivot member
engaging said seat support at said slot such that said seat support
is pivotally and slidably connected to said housing about said
second horizontal axis.
7. The chair of claim 1 further comprising a pivot member mounted
to said seat support and defining said second horizontal axis and
wherein said housing has a slot, said seat support pivot member
engaging said housing at said slot such that said seat support is
pivotally and slidably connected to said housing about said second
horizontal axis.
8. The chair of claim 4 wherein said second horizontal axis is
positioned forwardly of said first horizontal axis which is
positioned forwardly of said third horizontal axis, whereby said
back support tilts rearwardly about said first horizontal axis at a
greater rate than said seat support tilts rearwardly about said
second horizontal axis.
9. The chair of claim 1 wherein said fulcrum member is adjustably
connected to and longitudinally moveable within said housing,
whereby said fulcrum member can be moved longitudinally within said
housing so as to engage said at least one leaf spring at various
points intermediate said first and second ends and thereby alter
the amount of resistance applied to the seat support as a user
tilts rearwardly on the seat.
10. The chair of claim 9 further comprising an adjustment member
rotatably connected to said housing and threadably engaging said
fulcrum member, whereby rotation of said adjustment member causes
said fulcrum member to move along a longitudinal path within said
housing to thereby alter the amount of resistance applied to the
seat support
11. The chair of claim 1 wherein said at least one leaf spring is
made of a composite material.
12. The chair of claim 11 wherein said composite material comprises
a fiber and binder matrix.
13. The chair of claim 1 wherein said at least one leaf spring
comprises a top surface operably engaging a bottom surface of a
cross member extending laterally across a front portion of said
housing at said first end of said at least one leaf spring.
14. The chair of claim 13 wherein said top surface operably engages
a pivot member pivotally connecting said seat support and said back
support at said second end of said at least one leaf spring.
15. The chair of claim 1 comprising a pair of parallel and
laterally spaced apart leaf springs extending longitudinally within
said housing, wherein each of said leaf springs comprises a first
end engaging said housing and a second end biasing said back
support and said seat support in an upward direction, and wherein
said fulcrum member engages each of said leaf springs between said
first and second ends.
16. The chair of claim 1 wherein said housing comprises a landing
and wherein said fulcrum member is slidably supported on said
landing and slidably engages a bottom surface of said at least one
leaf spring, whereby a user can slide said fulcrum member between
said landing and said leaf spring so as to alter the amount of
resistance applied to the seat support
17. The chair of claim 1 wherein said fulcrum member is made of a
plastic material
18. The chair of claim 17 wherein said fulcrum member is one
piece.
19. The chair of claim 1 wherein said fulcrum member comprises a
shaft and a roller mounted on said shaft, said roller engaging said
at least one leaf spring.
20. The chair of claim 19 wherein said fulcrum member further
comprises a second roller mounted on said shaft and wherein said
housing further comprises a landing, said second roller supported
on said landing.
21. The chair of claim 1 further comprising a seat adjustably
mounted on said seat support, whereby said seat can be moved in a
longitudinal direction relative to said seat support.
22. The chair of claim 21 wherein said seat comprises a seat pan
having a pair of channels, and said seat support further comprising
a pair of channels cooperating with said channels on said seat pan
so as slideably mount said seat pan on said seat support.
23. The chair of claim 22 wherein said seat support further
comprises a plurality of notches and said seat further comprises a
lever slidably mounted on said seat pan, said lever comprising a
nose adapted to engage one of said notches so as to releasably lock
said seat to said seat support
24. The chair of claim 1 further comprising a tilt limiter mounted
to said housing and operably engaging said seat support so as to
limit the rearward tilting of said seat support.
25. The chair of claim 24 wherein said tilt limiter comprises a cam
member pivotally attached to said housing, and wherein said seat
support further comprises a rack, wherein said cam member is
adapted to operably engage said rack as said seat support pivots
rearwardly about said second horizontal axis, whereby said cam
member can be pivoted to a desired location so as to limit the
maximum rearward tilting of the chair by engagement of said cam
member with said rack.
26. The chair of claim 1 further comprising a forward bias member
mounted to said seat support and adapted to operably engage said
housing to limit the forward tilting of the seat.
27. The chair of claim 26 wherein said forward bias member
comprises a rod rotatably connected to said seat support and a cam
member extending from said rod and engaging said housing, said cam
members pivotable between at least a normal seating position and a
forward bias seating position.
28. A chair comprising: a three bar mechanism having a sliding
pivot comprising a housing having a first and second pivot axes and
forming a first bar between said first and second pivot axes, a
back support pivotally connected to said housing at said first
pivot axis and having a third pivot axes, said back support forming
a second bar between said first and third pivot axes, and a seat
support pivotally connected to said back support at said third
pivot axis and pivotally and slideably connected to said housing at
said second pivot axis, said back support forming a third bar
between said second and third pivot axes; and at least one leaf
spring comprising a first end engaging said housing and a second
end biasing said back support and said seat support in an upward
direction
29. The chair of claim 28 further comprising a fulcrum member
moveably supported in said housing and engaging said at least one
leaf spring between said first and second ends, whereby said
fulcrum member can be longitudinally moved within said housing so
as to engage said pair of leaf springs at various points
intermediate said first and second ends and thereby alter the
amount of resistance applied to the seat support as a user tilts
rearwardly on the seat
30. A chair comprising: a housing; a back support pivotally
connected to said housing about a first horizontal axis; a seat
support pivotally connected to said housing about a second
horizontal axis, and pivotally and slidably connected to said
housing about a third horizontal axis; at least one leaf spring
extending longitudinally within said housing and comprising a first
end engaging said housing and a second end biasing said back
support and said seat support in an upward direction; and a fulcrum
member moveably supported by said housing and engaging said at
least one leaf spring between said first and second ends; whereby
said fulcrum member can be moved so as to engage said at least one
leaf spring at various points intermediate said first and second
ends and thereby alter the amount of resistance applied to said
back support and said seat support as a user tilts rearwardly on
the chair.
31. A chair comprising: a housing; a seat support pivotally
attached to said housing; a back support pivotally connected to
said seat support and comprising a pair of upwardly extending and
spaced apart uprights and a cross member connecting said uprights;
a backrest slidably mounted on said uprights; an armrest slidably
mounted on each of said uprights; at least one leaf spring
comprising a first end engaging said housing and a second end
biasing said back support and said seat support in an upward
direction, and a fulcrum member moveably supported in said lousing
and engaging said at least one leaf spring intermediate said first
and second ends
32. The chair of claim 31 further comprising a seat adjustably
mounted to said seat support, wherein said seat can be moved
between a forward and rearward position to vary the distance
between a front edge of the seat and the back support.
33. A chair comprising: a back support comprising at least one
upright, a first and second bar member mounted to said upright in a
parallel and spaced apart relationship with each other; a backrest
slidably mounted on said first bar member; an armrest slidably
mounted on said second bar member.
34. The chair of claim 33 wherein said upright comprises a channel,
and wherein said first and second bar members are disposed in said
channel.
35. The chair of claim 34 wherein said backrest comprises a bracket
slideably mounted on said first bar member.
36. The chair of claim 35 further comprising an engagement member
pivotally attached to said bracket, and wherein said upright
further comprises a rack formed in a base portion of said channel,
said engagement member adapted to operably engage said rack to
releasably secure said backrest in a desired position.
37. The chair of claim 33 wherein said second bar member has a
plurality of notches formed along a portion thereof, and wherein
said armrest comprises a locking device adapted to operably engage
at least one of said plurality of notches to releasably secure said
armrest in a desired position
38. The chair of claim 37 wherein said locking device comprises a
latch member comprising a protuberance adapted to engage said at
least one of said plurality of notches, said latch member slidably
mounted in said armrest, said latch member moveable between an
engaged position wherein said protuberance is received within said
at least one of said plurality of said notches, and a disengaged
position wherein said protuberance is disengaged from said at least
one of said plurality of notches.
39. The chair of claim 38 wherein said latch member includes a
wedge shape portion with a first surface adapted to engage said
second bar member and a second surface forming an oblique angle
with said first surface, said protuberance disposed on said first
surface, and wherein said armrest has a wall forming an oblique
angle with said second bar member and defining a cavity shaped to
receive said latch member, said second surface of said latch member
adapted to slidably engage said wall when said latch member is
disposed in said cavity between said wall and said second bar
member, whereby said second surface of said latch member can be
slid downwardly relative to said wall to disengage said
protuberance from said notch, and whereby said wedge shaped portion
releasably secures said armrest against said second bar member when
in said engaged position.
40. The chair of claim 33 wherein said armrest includes a base
portion having a vertically oriented passage shaped to receive said
second bar member, said base portion slidably mounted on said
second bar member at said passage, said armrest further comprising
a latch member having a wedge shaped portion with a first surface
adapted to engage said second bar member and a second surface
forming an oblique angle with said first surface and wherein said
base portion of said armrest has a wall forming an oblique angle
with said second bar member and defining a cavity shaped to receive
said latch member, said second surface of said latch member adapted
to slidably engage said wall when said latch member is disposed in
said cavity between said wall and said second bar member, whereby
said second surface of said latch member can be slid downwardly
relative to said wall to disengage said latch member and thereby
allow said armrest to be moved along the length of the second bar
member to a desired position, and whereby said wedge shaped portion
biases said armrest against said second bar member when in said
engaged position to thereby frictionally secure said armrest to
said second slide member.
41. The chair of claim 33 wherein said second bar member comprises
a rack, and wherein said armrest comprises a latch member adapted
to operably engage said rack at a desired location.
42. The chair of claim 41 herein said latch member is pivotally
attached to said armrest.
43. The chair of claim 33 wherein said back support comprises a
pair of uprights extending along opposite sides of the backrest, a
pair of first and second bar members attached to each of said pair
of uprights, and a pair of armrests mounted on said second bar
members.
44. A chair comprising: a housing; a seat support pivotally
attached to said housing; a back support pivotally connected to
said housing and comprising a pair of upwardly extending and spaced
apart uprights and a cross member connecting said uprights; a
backrest slidably mounted on said uprights; an armrest slidably
mounted on each of said uprights; whereby said back support can be
tilted rearwardly and whereby said back and said armrests can each
be slideably adjusted on said back support.
45. A chair comprising: a back support comprising at least one
upright having a longitudinal groove and a rack formed adjacent to
said groove, a spline member having a tongue slideably received
within said groove; a backrest mounted to said spline, a latch
member mounted to said backrest and adapted to operably engage said
rack whereby said backrest can be releasably secured in a desired
position.
46. A chair comprising: a back support comprising at least one
upright having a channel; an armrest having a portion slidably
mounted to said upright in said channel; a backrest mounted to said
upright and covering said channel so as to substantially conceal
the portion of the armrest mounted therein.
47. The chair of claim 46 wherein said backrest is attached to a
bracket, said bracket slideably mounted to said upright in said
channel.
48. An adjustable armrest for a chair having a rack, said armrest
comprising: a base portion having a cavity defined by a front wall;
and a locking device disposed in said cavity, said locking device
comprising a latch member slideably mounted in said cavity, said
latch member comprising a wedge shaped portion having a first and
second surface forming an oblique angle between them and a
protuberance shaped to selectively engage said rack, said
protuberance disposed on said first surface and said second surface
slideably engaging said front wall of said base portion whereby
said latch member is moveably between an engaged position wherein
said protuberance selectively engages said rack and a disengaged
position wherein said protuberance is disengaged from said rack,
whereby said second surface of said latch member can be slid
downwardly along said front wall to disengage said protuberance
from said rack.
49. A chair comprising: a housing; a seat pivotally mounted to said
housing, said seat pivotable to a plurality of tilt positions; a
tilt limiter engaged between said seat and said housing, said tilt
limiter limiting the rearward tilting of the seat relative to the
housing, said tilt limiter moveable between a plurality of
settings, wherein a maximum rearward tilt position of said seat is
determined by the setting of the tilt limiter, said seat having a
plurality of maximum rearward tilt positions corresponding to said
plurality of settings for said tilt limiter; and a selector member
connected to said tilt limiter, said selector member comprising
indicia for indicating the setting of the tilt limiter, whereby the
user is apprised of the maximum rearward tilt position of the seat
corresponding to the indicated setting of the tilt limiter even
when said tilt position of said seat is other than the maximum
rearward tilt position of the seat.
50. The chair of claim 49 wherein said selector member comprises a
handle having a substantially horizontal axis of rotation and
wherein said indicia are formed on said handle.
51. The chair of claim 50 wherein said selector is moveable to a
plurality of angular positions about said horizontal axis of
rotation corresponding to the plurality of settings of said tilt
limiter, whereby said angular position of the indicia on said
handle indicates the setting of the tilt limiter.
52. The chair of claim 50 wherein said handle comprises a
substantially flat elongated portion, said substantially flat
elongated portion forming said indicia, whereby the angular
position of said elongated portion indicates the setting of the
tilt limiter.
53. The chair of 24 further comprising a selector member connected
to said tilt limiter, and wherein said tilt limiter is moveable
between a plurality of settings such that a maximum rearward tilt
position of said seat support is determined by the setting of the
tilt limiter, said seat support having a plurality of maximum
rearward tilt positions corresponding to said plurality of settings
for said tilt limiter, said selector member comprising indicia for
indicating the setting of the tilt limiter, whereby the user is
apprised of the maximum rearward tilt position of the seat
corresponding to the indicated setting of the tilt limiter even
when said tilt position of said seat is other than the maximum
rearward tilt position of the seat.
54. A chair comprising: a housing; a seat pivotally mounted to said
housing, said seat pivotable to a plurality of tilt positions; a
tilt limiter engaged between said seat and said housing, said tilt
limiter limiting the rearward tilting of the seat relative to the
housing, said tilt limiter moveable between a plurality of
settings, wherein a maximum rearward tilt position of said seat is
determined by the setting of the tilt limiter, wherein said seat
has a plurality of maximum rearward tilt positions corresponding to
said plurality of settings for said tilt limiter; and means for
indicating the setting of the tilt limiter, whereby the user is
apprised of the maximum rearward tilt position of the seat
corresponding to the indicated setting of the tilt limiter even
when said tilt position of said seat is other than the maximum
rearward tilt position of the seat.
Description
BACKGROUND OF THE INVENTION
[0001] The present invention relates generally to tiltable chairs,
and in particular, to a synchrotilt chair having an adjustable
seat, backrest and armrests.
[0002] Chairs of the type typically used in offices and the like
are usually configured to allow tilting of the seat and backrest as
a unit, or to permit tilting of the backrest relative to the seat.
In chairs having a backrest pivotally attached to a seat in a
conventional manner, the movement of the backrest relative to the
seat can create shear forces which act on the legs and back of the
user, and which can also create an uncomfortable pulling of the
user's shirt, commonly called "shirt-pull."
[0003] To enhance the user's comfort and to promote ergonomically
healthy seating, synchro-tilt chairs provide for the seat and
backrest to tilt simultaneously, but at different rates, preferably
with the back tilting at a greater rate than the seat. Normally,
synchro-tilt chairs employ compression and/or tension springs,
torsion springs and/or torsion bars to bias the seat and back
upwardly and to counterbalance the rearward tilting of the user
Chairs using these types of springs can have various limitations
associated with the type of spring used therein.
[0004] For example, the proper placement of compression springs
and/or torsion springs within the chair can often require a large
or bulky housing with associated aesthetic limitations. Moreover,
the ride, or resistive force experienced by the user, may be
unsatisfactory because spring rates associated with compression
springs are not linear and tend to increase as the spring bottoms
out In addition, the cost of manufacturing the chair, due to the
placement of the springs and the introduction of additional load
bearing elements, can be increased This problem can be exacerbated
when two or more springs are used in the chair Moreover,
synchrotilt chairs typically provide for the spring to act on one
of the seat or back support, and for the force to then be
transferred to the other through a pivotal attachment, which can
require additional load carrying capabilities.
[0005] Furthermore, inconsistencies in the performance of
compression and torsion springs, and the longevity thereof, can
often be traced to the inherent properties of steel, which is
typically used to make such springs. For example, steel is
subjected to the problem of "creep" and various inconsistencies
introduced during the manufacture of the steel and the subsequent
heat-treating processes. Moreover, because of the requisite size of
the springs, the mechanisms used to adjust the amount of initial
resistive compression can be difficult to activate, and can be
progressively more difficult to adjust as higher settings are
reached.
[0006] Chairs employing torsion bars may experience similar
limitations. For example, the length and diameter of the bar is
dictated by the range of movement and force output desired, and the
desire to avoid overstressing the spring. Often, relatively heavy
and highly stressed bars of great length are required to provide
the control necessary to adequately support a user. Thus, the shape
and associated aesthetics of the chair are dictated by the size of
the spring. In addition, the chair must be provided with
load-bearing elements at the ends of the bar and at the point of
adjustment. Moreover, as with compression and torsion springs,
activation or adjustment mechanisms used to achieve a desired
initial pretorque setting can be difficult to manipulate, and can
become increasingly so as higher settings are reached.
[0007] Leaf springs can also be used to support the user in the
chair. However, leaf springs are typically clamped at one or more
ends of the spring, usually by passing a bolt or like fastener
through the spring. This is especially true when the leaf spring is
configured as a cantilever similar to a diving board Holes in the
spring can introduce stress risers, however, and clamping one or
more ends, as opposed to having them simply supported, introduces
indeterminate moments and resultant stresses in the spring which
may not be evenly distributed Moreover, the resistive force of many
leaf springs, including cantilevered springs, is often adjusted by
varying the prestress of the spring through bending As with the
other springs described above, such an adjustment mechanism can be
difficult to activate, and becomes progressively more so as higher
settings are reached.
[0008] It is also desirable to provide a chair that can be adjusted
to accommodate the various needs and sizes of the user. In
particular, it is desirable to provide a chair having an adjustable
backrest, adjustable armrests, and an adjustable seat depth.
[0009] The typical approach to adjustably supporting a backrest is
to provide a single, centered spline, which can be located
internally or externally to the backrest cushion, or like support.
Typically, such a spline is linear so as to allow for adjustment of
the backrest. However, it is often desirable to provide contours in
the backrest of the chair so as to conform to the shape of the
user's back. When the spline is located inside the backrest, the
assembly is necessarily thick to accommodate the spline and desired
contour. In addition, the backrest must itself be structural, and
securely attached to the spline with tight tolerances, to provide
lateral support for the user on the outer edges of the backrest and
to avoid a feeling of sloppiness. Moreover, if armrests are
desired, they must typically be positioned on separate supports
projecting from the seat or from beneath the chair, since the
spline centered backrest is usually structurally unable to support
the large loads imparted on the armrests by a user along the sides
of the backrest. When adjustable, such armrest supports often house
complex and expensive to manufacture height adjustment
mechanisms.
[0010] Furthermore, synchrotilt chairs typically provide pivot axes
and links along the sides of the chair. Mechanically, there is an
advantage to give the driven links input (occupant) and output
forces (e.g., springs) as great a relative "stance" as possible. As
a result, the use of a centered spline can result in a control that
feels less "lively" when the occupant is not centered.
Additionally, centered spline chairs often provide an adjustment
mechanism adjacent the spline at the center of the back, which can
be difficult to access, especially by a seated occupant when the
backrest is in a lowermost position.
SUMMARY OF THE INVENTION
[0011] Briefly stated, the invention is directed to an improved
synchrotilt chair having an improved tilt control mechanism and an
adjustable backrest, armrests and seat.
[0012] In one aspect of the invention, the chair includes a
housing, a back support pivotally connected to the housing about a
first horizontal axis and a seat support pivotally connected the
housing about a second horizontal axis. A leaf spring includes a
first end engaging a forward portion of the housing and a second
end biasing the seat support and the back support in an upward
direction. A fulcrum member is moveably supported in the housing
and engages the leaf spring between its first and second end. In
operation, the fulcrum member can be easily moved longitudinally
within the housing so as to vary the length of the leaf spring
lever arm and thereby vary the amount of resistive force supporting
the user.
[0013] In a preferred embodiment, the seat support is also
slideably connected to the housing about the second horizontal axis
and is pivotally connected to the back support about a third
horizontal axis.
[0014] In another aspect of the invention, a seat having a seat pan
is adjustably mounted on the seat support. In operation, the seat
can be moved in a longitudinal direction to adjust the depth of the
seat relative to the backrest and thereafter releasably locked to
the seat support.
[0015] In yet another aspect of the invention, a tilt limiter is
provided to limit the rearward tilting of the chair. The tilt
limiter includes a cam member pivotally mounted in the housing and
having a plurality of teeth which engage a rack, or plurality of
laterally oriented grooves, formed in the seat support. In
operation, the cam member can be pivoted to limit the rearward
tilting of the user.
[0016] In another aspect of the invention, a selector member is
connected to the tilt limiter. The selector member includes indicia
that indicates the setting of the tilt limiter so as to apprise the
user of the maximum rearward tilt position of the seat, or chair,
even when the seat or chair is in a tilt position other than the
maximum rearward tilt position. In a preferred embodiment, the
selector member comprises a handle connected to the cam member The
handle preferably has an substantially flat elongated portion
forming the indicia such that the angular orientation of the
substantially flat elongated portion indicates the setting of the
tilt limiter, and the corresponding maximum rearward tilt position
of the seat and chair.
[0017] In another aspect of the invention, the back support
includes a pair of uprights extending upwardly along opposite sides
of the chair. Each upright includes a first and second bar mounted
thereto in a parallel and spaced apart relationship with the other.
A backrest is slideably mounted on the first bar members and an
armrest is slideably mounted to each of the second bar members.
Preferably, the uprights are located externally of the backrest and
are connected with a cross member so as to form a one-piece back
support.
[0018] In a preferred embodiment, an engagement member is mounted
to a bracket member which is mounted on the first bar member. The
engagement member is adapted to engage a rack located on the
upright to thereby releasably secure the backrest to the uprights.
The armrest preferably includes a locking device which is adapted
to engage the second bar member and thereby releasably secure the
armrest to the upright.
[0019] The present invention provides significant advantages over
other synchrotilt chairs, and chairs having adjustable backrests
and armrests. For example, in the most preferred embodiment, an
improved tilt control mechanism is provided which can be
manufactured in a compact and aesthetically pleasing housing. In
particular, the leaf spring, or preferably a pair thereof, extends
longitudinally within the housing, which can be made in a compact
and aesthetically pleasing form with little or no depth due to the
nature of the spring The width of the housing also need not be
dictated by length of the spring The resistive force of the leaf
springs is easily and simply adjusted by moving the fulcrum member
longitudinally within the housing Consequently, the springs are not
prestressed at differing levels, and the adjustment member can be
easily manipulated without progressive difficulty The leaf spring
also provides a relatively uniform spring rate throughout the
tilting range of the chair.
[0020] The leaf springs also are preferably made of composite
material, which is more resistant to creep. The leaf spring
preferably supports a shaft pivotally connecting the seat support
and back support. In this way, the leaf spring biases both members
upwardly together, rather than acting oil one member with the force
then transmitted to the other member through a pivotal attachment.
As such, the number of load bearing elements are reduced and
simplified.
[0021] The three bar slide mechanism also provides several
advantages. For example, the linkage provides for a synchrotilt
chair wherein the back tilts at a greater rate than the seat, but
avoids the use of a fourth bar, which can add to the complexity and
manufacturing costs of the chair. Indeed, the overall design is
greatly simplified by forming "bars" out of the housing, seat
support and back support. Additionally, the use of a slide member
allows for the assembly to be made in a more compact and
aesthetically pleasing form.
[0022] The unique back support also provides many advantages. For
example, by providing a one-piece back support, a simplified and
aesthetically pleasing structure is provided, which also performs
the combined tasks of forming one of the bars of the linkage
assembly, providing a support for the backrest and providing a
support for the armrests. Additionally, the exoskeletal nature of
the back support framing a cushion gives the user a strong visual
of support, security and durability. Moreover, by providing
uprights along the sides of the chair, the backrest is not required
to be structural in nature, and the loads imparted by a user
against the side of the backrest can be transmitted directly
through the forwardly extending arms of the back support to the
housing and spring member so as to provide a more "lively" control
for the user. Moreover, since the backrest is supported on both
sides, looser tolerances can be accommodated during the assembly of
the backrest without sacrificing any tightness in the feel of the
backrest.
[0023] The uprights can also be used to also support the armrests,
which thereby avoids the need for separate supports and complex
mechanisms In this regard, the bar members, which are mounted to
the uprights, provide a simple but sturdy support for the backrest
and armrests.
[0024] The present invention, together with further objects and
advantages, will be best understood by reference to the following
detailed description taken in conjunction with the accompanying
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] FIG. 1 is a front perspective of the chair with the
backrest, seat cushion and seat pan shown in an exploded
format.
[0026] FIG. 2 is a front view of the chair without a backrest, seat
cushion or armpads applied thereto.
[0027] FIG. 3 is a side view of the chair without a backrest, seat
cushion or armpads applied thereto.
[0028] FIG. 3A is a partial side view of an alternative embodiment
of the pivotal connection between the seat support and the
housing.
[0029] FIG. 4 is a partial bottom view of the chair taken along
line 4-4 of FIG. 3 without armrests applied thereto.
[0030] FIG. 5 is a partial top view of the chair taken along line
5-5 of FIG. 3 without armrest applied thereto.
[0031] FIG. 6 is a cross-sectional view taken along line 6-6 of
FIG. 4.
[0032] FIG. 6A is an alternative view of a section of the chair
with a forward bias space applied thereto.
[0033] FIG. 7 is a cross-sectional view taken along line 7-7 of
FIG. 4
[0034] FIG. 8 is a cross-sectional view taken along line 8-8 of
FIG. 4 without the back support shown.
[0035] FIG. 9 is a cross-sectional view taken along line 9-9 of
FIG. 4 without the back support shown.
[0036] FIG. 9A is a partial cross-sectional view of an alternative
embodiment of the connection between the seat support and the
housing FIG. 10 is a top view of the seat support FIG. 11 is a side
view of the seat support FIG. 12 is a cross-sectional view of the
seat support taken along line 12-12 of FIG. 10
[0037] FIG. 12A is an alternative embodiment of the seat support
shown in FIG. 12.
[0038] FIG. 13 is a cross-sectional view of the seat support taken
along line 13-13 of FIG. 10.
[0039] FIG. 14 is a partial enlarged cross-sectional view of a
portion of the seat support shown in FIG. 13.
[0040] FIG. 15 is a partial view of the forward bias spacer mounted
to the seat support.
[0041] FIG. 16 is a cross-sectional view of the seat support and
housing with the tilt limiter in a reclined tilt position.
[0042] FIG. 17 is a cross-sectional view of the seat support and
housing with a tilt limiter in an intermediate tilt position.
[0043] FIG. 18 is a cross-sectional view of the seat support and
housing with a tilt limiter in a upright tilt position and the
forward bias device in the normal seating position.
[0044] FIG. 19 is a perspective view of the housing with a fulcrum
member, one of the leaf springs and the tilt limiter applied
thereto
[0045] FIG. 20 is a partial rear perspective view of the tilt
limiter and pneumatic cylinder adjustment mechanism.
[0046] FIG. 21 is an exploded view of the tilt mechanism.
[0047] FIG. 22 is a bottom view of the seat pan.
[0048] FIG. 23 is a cross-sectional view of the seat pan taken
along line 23-23 of FIG. 22.
[0049] FIG. 24 is a front view of a fulcrum member.
[0050] FIG. 24A is a partial front view of an alternative
embodiment of the fulcrum member.
[0051] FIG. 25 is a top view of the fulcrum member
[0052] FIG. 26 is a partial sectional view of an alternative
embodiment of the fulcrum member supported on the housing
[0053] FIG. 27 is a schematic of the tilt mechanism in an upright
position with the leaf spring shown in an unstressed and
prestressed positions
[0054] FIG. 28 is a schematic of the tilt mechanism shown in a
reclined tilt position with the fulcrum positioned forwardly in the
housing.
[0055] FIG. 29 is a schematic of the tilt mechanism shown in a
reclined position with the fulcrum member positioned rearwardly in
the housing
[0056] FIG. 30 is a bottom perspective view of the housing, seat
support, seat pan and partial back support.
[0057] FIG. 31 is a partial top perspective view of the adjustment
mechanism for the seat pan.
[0058] FIG. 31A is perspective view of an alternative adjustment
mechanism for the seat pan.
[0059] FIG. 32 is a front view of the back support.
[0060] FIG. 33 is a top view of the back support.
[0061] FIG. 34 is a cross-sectional view of the back support taken
along line 34-34 of FIG. 32.
[0062] FIG. 35 is a cross-sectional view of the upright taken along
line 35-35 FIG. 32.
[0063] FIG. 36 is an exploded view of the back support, bar member,
bracket, engagement member and spring.
[0064] FIG. 37 is an exploded view of the armrest and locking
device.
[0065] FIG. 37A is a partial view of an alternative embodiment of
the armrest.
[0066] FIG. 38 is an enlarged perspective view of the locking
device.
[0067] FIG. 39 is a partial front view of the back support with a
first and second bar member and an armrest and backrest bracket
applied thereto.
[0068] FIG. 40 is a cross-sectional view of the back support and
armrest taken along line 40-40 of FIG. 39
[0069] FIG. 40A is an enlarged view of the armrest locking device
shown in FIG. 40.
[0070] FIG. 41 is a cross-sectional view of the back support,
backrest bracket and armrest taken along line 41-41 of FIG. 39
[0071] FIG. 42 is a perspective view of a latch member
[0072] FIG. 43 is a partial perspective view of an alternative
embodiment of the locking device for the armrest.
[0073] FIG. 44 is a front view of an alternative embodiment of a
locking device for the backrest.
[0074] FIG. 45 is a side view of the locking device shown in FIG.
44.
[0075] FIG. 46 is an alternative embodiment of the locking device
for the armrest.
[0076] FIG. 47 is an alternative embodiment of the locking device
for the armrest.
[0077] FIG. 48 is an alternative embodiment of the locking device
for the armrest.
[0078] FIG. 49 is an alternative embodiment of the locking device
for the armrest.
[0079] FIG. 50 is an alternative embodiment of the locking device
for the armrest.
[0080] FIG. 51 is an alternative embodiment of the locking device
for the armrest.
[0081] FIG. 52 is an alternative embodiment of the locking device
for the armrest.
[0082] FIG. 53 is an alternative embodiment of the back support and
armrest
[0083] FIG. 54 is a partial exploded view of the backrest
adjustment mechanism shown in FIG. 53.
[0084] FIG. 55 is a cross-sectional view of the back support and
backrest taken along line 55-55 of FIG. 53.
[0085] FIG. 56 is an alternative embodiment of the locking device
for the armrest.
[0086] FIG. 57 is a bottom view of an alternative embodiment of the
s eat support.
[0087] FIG. 58 is a partial side view of the back with the seat
shown at a maximum rearward tilt position comprising a forward tilt
position and having a selector member and indicia positioned to
indicate that the tilt limiter is in the forward tilt position.
[0088] FIG. 59 is a partial side view of the chair with the seat
shown at a maximum rearward tilt position comprising an upright
tilt position and having a selector member and indicia positioned
to indicate that the tilt limiter is in the upright tilt
position.
[0089] FIG. 60 is a partial side view of the chair with the seat
shown at a maximum rearward tilt position comprising one of a
plurality of intermediate tilt positions and having a selector
member and indicia positioned to indicate that the tilt limiter is
in one of the plurality of intermediate tilt positions.
[0090] FIG. 61 is a partial side view of the chair with the seat
shown at a maximum rearward tilt position comprising another of the
plurality of intermediate tilt positions and having a selector
member and indicia positioned to indicate that the tilt limiter is
in another of the plurality of intermediate tilt positions.
[0091] FIG. 62 is a partial side view of the chair with the seat
shown at a maximum rearward tilt position comprising a reclined
tilt position and having a selector member and indicia positioned
to indicate that the tilt limiter is in the reclined tilt
position.
DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS
[0092] The terms "longitudinal" and "lateral" as used herein are
intended to indicate the direction of the chair from front to back
and from side to side, respectively. Similarly, the terms "front",
"side", "back", "forwardly", "rearwardly", "upwardly" and
"downwardly" as used herein are intended to indicate the various
directions and portions of the chair as normally understood when
viewed from the perspective of a user sitting in the chair.
[0093] Referring to the drawings, FIG. 1 shows a preferred
embodiment of the chair having tilt control housing 10, seat
support 20, seat cushion 22, back support 30, backrest 32 and seat
pan 24 A pneumatically adjustable support column 12 is mounted to a
rear portion of the housing at opening 14 as shown in FIGS. 4 and 6
A top portion of the column 12 having an actuation button extends
into the housing. As shown in FIGS. 19-21, a pivot member 34 having
a forwardly extending arm 36 engaging a stop 40 and a rearwardly
extending arm 38 adapted to engage the actuation button is mounted
to a pivot rod 42 by engagement of a key member within a key hole.
The pivot rod is rotatably mounted to housing 10 at lug member 166.
A handle 44 is mounted to the end of the pivot rod 42. In
operation, the handle 44 is rotated so as to rotate the rearwardly
extending arm 38 of the pivot member and thereby engage the
actuation button, which in turn allows the support column to extend
in response to a gas spring contained therein, or to collapse in
response to the weight of the user being applied to the seat.
[0094] Referring to FIG. 1, a base 16, preferably a five arm base
with casters, is mounted to the bottom of the support column 12 in
a conventional manner. One of skill in the art would understand
that other support columns and bases can be used to support the
housing, including fixed height support columns and non-rolling
bases.
[0095] As shown in FIGS. 3 and 4, the back support 30 includes a
pair of support arms 50, extending forwardly along opposite sides
of the chair. Each of the support arms 50 terminates in a first lug
portion 52 having a horizontal opening 54. Referring to FIG. 19,
the housing 10 includes a boss 60 extending outwardly from each
sidewall 62 of the housing in a perpendicular relationship
therewith. The lug portions 52 are pivotally mounted to the bosses
60 on opposite sides of the housing with a pair of hollow pivot
rods 56, which are inserted through an opening 64 extending through
each boss and which defines a first horizontal pivot axis. The
pivot rod 42 for actuating the gas spring extends through and is
rotatably mounted in the hollow pivot rod 56.
[0096] As shown in FIGS. 3 and 30, each support arm also includes a
second lug portion 58 positioned rearwardly of said first lug
portion 52 The second lug portions 58 are pivotally connected to
the seat support with a pivot rod 66, which define a third
horizontal pivot axis, as shown in FIGS. 3 and 4.
[0097] Referring to FIG. 4, pivot rod 68 extends outwardly from
each sidewall 62 of the housing and defines a second horizontal
axis The seat support 20 is pivotally and slideably connected to
the housing at the second horizontal pivot axis by inserting the
pivot rods through slots 30 formed in opposite sidewalls 67 of the
seat support as shown in FIG. 3A. Alternatively, the pivot rods 68
are disposed in slotted channels 72 formed in each of the sidewalls
as shown in FIG. 9. Or, in yet another alternative embodiment,
shown in FIG. 9A, pivot rod 74 extends inwardly from the seat
support sidewall to engage a slot 76 formed in the sidewall of the
housing. In a preferred embodiment, the second horizontal pivot
axis 68 is positioned forwardly of the first horizontal pivot axis
56, which is positioned forwardly of the third horizontal pivot
axis 66.
[0098] In operation, the housing 10, seat support 20 and back
support 30 form a three-bar linkage with a slide. Because the
second pivot axis is positioned forwardly of the first pivot axis
which is positioned forwardly of the third pivot axis, the back
support 30 tilts rearwardly at a greater rate and angle than does
the seat support 20. Preferably, the back to seat inclination is at
a ratio of about 2:1. The three-bar linkage provides a simple and
compact mechanism which avoids the use of additional links.
Additionally, by forming the linkage assembly from the seat
support, back support and housing, complex and expensive links and
load bearing parts are avoided. When combined with a pair of leaf
springs 80, the resultant chair can be designed in a compact and
aesthetically pleasing form. It should be understood that the
three-bar linkage could be formed by pivotally connecting the seat
support and back support to the housing and by pivotally and
slideably connecting the seat support to the back support, or by
pivotally connecting the seat support to the housing and to the
back support and then pivotally and slideably connecting the back
support to the housing Although the above-described three-bar
mechanism is preferred, it should be understood that the leaf
springs can also be incorporated into synchro-tilt chairs using
linkage mechanisms such as four-bar linkages and the like With a
four-bar linkage, links can be provided to pivotally connect the
seat support and/or back support to the housing and/or to each
other about various horizontal axes.
[0099] As best shown in FIGS. 6-9, 19 and 27-29, a fulcrum member
90 is moveably installed in the housing 10 beneath the pair of leaf
springs 80 The fulcrum member 90 is preferably formed from a single
piece of hard, durable material having a relatively low coefficient
of friction, such as DELRIN or CELCON Acetal, so as to allow the
fulcrum member to slide relatively easily along a bottom surface of
the housing, even when heavily loaded by the spring It should be
understood, however, that other materials such as steel would also
work. Similarly, the bottom surface can be lined with a material
having a low coefficient of friction, such as TEFLON. Referring to
FIGS. 24 and 25, the fulcrum member 90 includes a bottom surface 92
and a pair of support pads 94 formed on a top of the fulcrum
member. Preferably, the support pads 94 on each side of the fulcrum
member are separated by a groove 96 which reduces the surface area
in contact with the spring 80 and the attendant friction forces
which act on the spring.
[0100] The fulcrum member 90 also includes end portions 98 which
are tapered outwardly and downwardly from the support pads 94, and
a lug portion 100 formed at a bottom center portion of the member.
Alternatively, as shown in FIG. 24A, the end portions include a
small lip portion 760. The lug portion 100 includes a
longitudinally oriented hole 102 In one embodiment, at least a
portion of the hole is threaded. Alternatively, a threaded fitting
can be inserted into the bore provided in the lug portion or a
entirely separate bracket having a threaded opening can be mounted
to a bottom of the fulcrum member.
[0101] As shown in FIGS. 5-9 and 19, the fulcrum member 90 is
disposed laterally within the housing 10 such that the bottom
surface 92 of the fulcrum member slideably engages a pair of
longitudinally oriented landings 107 formed along opposite sides of
the bottom of the housing. The end portions 98 of the fulcrum
member 90 abut the inner surface of the side walls 62 of the
housing and act as guides for the fulcrum member as it is moved
longitudinally within the housing Referring to FIG. 9, the lug
portion 100 is disposed within a channel 104 longitudinally formed
in the housing below and between the landings 102 The lug portion
100 also acts as a guide within the channel 104 so as to maintain
the alignment of the fulcrum member within the housing as it moves
longitudinally along its path.
[0102] In an alternative embodiment, shown in FIG. 26, the fulcrum
member 106 includes a shaft 108 and a carriage 110 disposed on the
shaft. A pair of rollers 112 are rotatably mounted on the shaft 108
so as to be in alignment with the pair of leaf springs 80. Two
pairs of support rollers 114 are rotatably mounted on the shaft on
opposite sides of each of the rollers 112 in alignment with
landings 116 formed on a bottom surface of the housing. In
operation, the fulcrum member can be rolled longitudinally within
the housing on rollers 114, as rollers 112 engage leaf springs 80.
A clip 118, or like retainer, is installed on each end of the shaft
to capture and retain the rollers and carriage on the shaft.
Preferably, the shaft, rollers and carriage are made of steel.
[0103] As illustrated in FIGS. 5, 6 and 16-18, an adjustment member
120, preferably a threaded shaft, is inserted through an opening
122 in a front wall 124 of the housing and is rotatably secured
thereto. A knob 126 is mounted on an end of the adjustment member
120 externally of the housing for access by the user. An opposite
end of the shaft is rotatably supported by a stop member 40
extending upwardly from the bottom surface of the housing. It
should be understood, however, that the end of the shaft need not
be supported at all as the fulcrum member is guided by the housing.
The shaft threadably engages the opening in the lug portion 100 of
the fulcrum member, or an opening in the carriage 110.
[0104] It should also be understood that the fulcrum member can be
fixed within the housing at a specific location, such that the
resistive force of the chair can not be adjusted.
[0105] As shown in FIG. 19, the front wall 124 of the housing
includes laterally oriented slotted openings 126 formed along
opposite sides of the front wall 124 of the housing. Cross members
130 are defined by and formed over the openings The pair of leaf
springs 80 are installed in the chair by inserting an end 82 of
each spring through one of the openings 128 such that a top surface
86 of the spring engages the cross member 130. Alternatively, as
shown in FIGS. 27-29, a horizontal rod 88 can be installed
laterally in a forward portion of the housing so as to engage the
top surface 86 of the forward end 82 of the spring In one
embodiment, a forward edge of the spring abuts the front wall of
the housing so as to maintain the longitudinal position of the
spring within the housing. Alternatively, as shown in FIG. 7, a
protuberance 132 extends downwardly from the cross member 130 and
engages a hole 134 or detent formed in a forward portion of the
spring so as to maintain the longitudinal position of the
spring.
[0106] The leaf springs 80 are constrained laterally within the
housing by the sides of the slotted opening at the front of the
housing and by the sides of a pair of openings 500, or notches,
formed in a rear vertical wall of the seat support as shown in
FIGS. 13 and 19. The leaf spring 80 extends rearwardly within the
housing 10 such that a bottom surface 87 engages the pad members 94
of the fulcrum member 90. An end 84 of the spring is inserted
beneath pivot rod 66 as shown in FIGS. 5 and 19 such that top
surface 86 engages pivot rod 66. Although each spring is shown as a
single leaf, it should also be understood that multi-leaf springs
could also be employed. The leaf springs are preferably made of a
composite material, such as a fiberglass and epoxy matrix, although
it should be understood that other resilient materials such as
steel would also work. The composite material can be a fibrous
composite, a laminated composite or a particulate composite. A
suitable composite spring is commercially available from Gordon
Plastics, Inc. of Montrose, Colo. under the specification
designation of GP68-UD Unidirectional Fiber Reinforced Bar Stock,
and sold under the tradename POWER-TUFF. The fiberglass/epoxy
matrix bar preferably is unidirectional with a glass content of
about 68% and a laminate density of 0.068 lbs./in..sup.3. The bar
preferably has a flexstrength of about 135,000 psi, a flex modulus
of about 5,000,000 psi, and an ultimate strain of about 2.4%. The
use of a composite material bar can help eliminate the problems
associated with creep.
[0107] In operation, the end 84 of the leaf spring biases pivot rod
66, and the pivotally connected back support 30 and seat support
20, in an upward direction so as to thereby support a user sitting
in the chair Since the leaf spring 80 acts on the pivot rod 66,
rather than on just one of the back support 30 or seat support 20,
the supports 20, 30 are not required to transmit the biasing force
to the other of the supports 20, 30, and can therefore be made less
robust and at less cost Rather, the bending loads are carried by
the pivot rod 66 Obviously it should be understood, however, that
the leaf spring could directly engage either the back support or
seat support so that the upwardly biasing force is transmitted to
the other thereof through the pivotal attachment. The opposite end
82 of the spring engages the cross member 130 or rod 88 mounted in
the housing, while the middle of the spring is supported by the
fulcrum member 90. In this way, the spring 80 acts as a simply
supported beam with a load imparted intermediate the supported ends
82, 84 thereof. To adjust the force applied to the pivot rod, the
user simply rotates the knob 126 which causes the adjustment member
120, or shaft, to rotate and thereby threadably engage the fulcrum
member so as to move it in a linear, longitudinal direction within
the housing.
[0108] As the fulcrum member 90 is moved rearwardly in the housing
10, the distance between the point of support and the pivot rod is
decreased as shown in FIG. 29, so as to correspondingly increase
the force applied by the end 84 of the spring. Conversely, as shown
in FIG. 28, the fulcrum member 90 can be moved forwardly in the
housing 10 to decrease the amount of resistive force applied to the
seat support and back support by increasing the beam length, or the
distance between the fulcrum 90 and the pivot rod 66. Since the
leaf spring 80 is simply supported at each end, rather being
clamped to the housing, the pivot rod or both, bending moments are
not introduced at the ends of the spring. When clamped, the
properties of the spring, and the amount of the clamping, can
effect the loading and associated stresses. Moreover, by providing
a simply supported spring, tolerances can be relaxed and the
curvature of the spring is allowed to undulate as the beam length
changes.
[0109] Because the leaf springs 80 are disposed in the housing 10
in a side-by-side arrangement, and are preferably formed as flat
bars, the housing can be made more compact at lower cost in an
aesthetically pleasing way This advantage is even more apparent
when the leaf spring arrangement is combined with the three bar
mechanism. Moreover, the resistive force of the spring can be
adjusted easily and simply by slideably moving the fulcrum 90
within the housing 10. Since the resistive force is determined by
the beam length, rather than by prestressing the spring, the
adjustment does not require a progressively larger actuation force
as is typically associated with torsion springs and bars and
compression springs.
[0110] Now turning to FIGS. 11-14, a rack 136 is shown as being
formed on a top of the seat support. The rack 136 consists of a
plurality of outwardly facing notches 138 formed along one side of
the seat support. The seat support also includes outwardly facing
channels 140 that run longitudinally along the top surface of the
seat support as shown in FIGS. 13 and 14.
[0111] A rack 142 is also formed on a bottom surface of the seat
support. The rack 142 is formed along a concave portion of the
bottom surface of the seat support and includes a plurality of
laterally extending grooves 144.
[0112] As shown in FIGS. 8 and 23, inwardly facing longitudinal
channels 26 extend downwardly from the seat pan 24 and are aligned
to communicate with and engage the outwardly facing channels 140 on
the seat support. The seat pan 24 is slideably mounted to the seat
support by slideably engaging the cooperating channels. In
addition, a pair of longitudinally aligned pins 506, or similar
protuberances, extend upwardly from the housing and are received in
a pair of slots 508, or channels, formed in the seat pan. The pins
prevent the seat pan from moving laterally with respect to the
housing such that the lateral tolerances between the interfitting
channels 26, 140 can be maintained rather loosely. Preferably, a
seat cushion 22 is attached to the seat pan 24. The travel of the
seat pan along a longitudinal path from front to back can be
limited either by the travel of the pin within the slots, or by
engagement of various stop members extending from one or both of
the seat support and seat pan.
[0113] As shown in FIGS. 30 and 31, a bracket member 146 is mounted
to a bottom of the seat pan with a plurality of fasteners engaging
holes in the seat pan A lever 148 having a handle and an inwardly
extending nose portion 150 is slideably mounted to the bracket
member The nose portion 150 is shaped to releasably engage the
notches 138 of rack 136 In operation, the user pulls the lever 148
outwardly to disengage the nose portion 150 from the rack 136 and
thereafter slides the seat cushion and seat pan 24 forwardly or
rearwardly with respect to the seat support 20 until a desired seat
depth position is reached The lever 148 is then pushed inwardly so
that the nose portion 150 engages one of the notches in the rack
136. The lever 148 can also be spring mounted so as to be biased
toward the rack and into the engaged position. The seat cushion is
attached to the seat pan.
[0114] Alternatively, as shown in FIGS. 9 and 31A, the nose portion
510 includes a notch 512 that is shaped to engage one of the ribs
514 forming the rack.
[0115] As shown in FIGS. 58-62, an information card 910 providing
indicia for using the various chair mechanisms can be slidably
mounted to the bracket 146. Preferably, the card and bracket are
provided with travel limiting members to prevent the card from
being removed from the chair where it can be then be lost.
[0116] Referring to FIGS. 16-18, a tilt limiter 152 is shown as
pivotally mounted to the housing on an axle 156. In one embodiment,
the tilt limiter includes a cam member 154 having a substantially
semi-circular shape with a convex upper surface shaped to
communicate with and to engage the concave rack 142 of the seat
support. The cam member is preferably one piece and is made from a
single piece of high impact plastic, although it should be
understood that other materials such as steel and other
combinations of parts would also work. In the one piece embodiment,
the axle is in-molded with the cam member. A bracket 182 is mounted
over the axle to capture it between the bracket and the housing A
plurality of fine, laterally oriented teeth 158 are formed along
the outer convex surface of the cam member. Teeth 158 engage the
rack 142 formed on the bottom of the seat support to limit the
rearward tilting of the seat support and chair.
[0117] In an alternative embodiment, shown in FIGS. 19-21, a
plurality of larger stepped teeth 159, or engagement surfaces, are
arranged around the periphery of the cam member 155. As shown in
FIGS. 12A and 57, the seat support includes a plurality of
longitudinally extending ribs 950 and a laterally extending rib 952
intersecting ribs 950. The cam member 155 can be rotated such that
one of the plurality of teeth 159 engages the ribs 950, 952 to
limit the rearward tilting of the seat support and chair.
[0118] Referring to FIGS. 16-21, a pivot rod 160 extends through
and is rotatably mounted within the hollow pivot rod 56 connecting
the back support 30 and the seat support 20 opposite pivot rod 42.
A handle 800 is secured to one end of the pivot rod 160 and can be
used to pivot the rod about a substantially horizontal axis. An
opposite end of the pivot rod 160 is mounted to a pivot member 162
and is rotatably supported by lug member 164. A forwardly extending
arm 168 of the pivot member 162 is pivotally connected to a
connecting member 170, preferably formed from a piece of wire,
which extends rearwardly to engage the cam member 154, 155. In
operation, the handle 800 and pivot rod 160 are rotated to pivot
the pivot member 162 and attached connecting member 170, which in
turn rotates the cam member about axle 156 to the desired tilt
position. As the user tilts rearwardly, the seat support 20 pivots
and slides about the third pivot axis 68 until the rack 142 is
brought into engagement with the teeth 158 on the cam member 154,
or until the ribs 950, 952 engage the teeth 159 of cam member 155,
wherein the seat support is prevented from tilting further
rearwardly. Since, as shown in FIGS. 16 and 21, the cam member 154,
155 is pivotally attached to the housing along an axis off-center
from the center of the approximately shaped arc formed by the
convex surface of the cam member, the user can pivot the cam member
about the off-center axis such that different sets of teeth 158
engage the rack 142 at various positions, or such that a different
stepped tooth 159 engages the ribs 950, 952, wherein the seat
support is engaged at varying desired tilt positions. For example,
as shown in FIGS. 58-62, the tilt limiter, including the cam
member, can be moved to a plurality of settings or positions so as
to limit the rearward tilting of the seat to a plurality of maximum
rearward tilt positions, including, but not limited to, a forward
tilt position, an upright tilt position, various intermediate tilt
positions and a reclined tilt position.
[0119] As shown in FIGS. 58-62, the handle 800 (also shown in FIG.
21), functions as a selector member for selecting the position of
the tilt limiter. In particular, the selector member is rotated so
as to rotate pivot rod 160, which in turn pivots the pivot member
162 and the connected cam member 154, 155 so as to vary the tilt
position thereof The selector member includes indicia 910 for
indicating the setting or position of the tilt limiter In
particular, as shown in the preferred embodiment of FIGS. 58-62,
the selector member includes an intergrally formed substantially
elongated flat portion 910 that extends laterally outward from and
radially across the face of the selector member. The flat portion
910 has upper and lower concave surfaces and is grippable by a user
for rotating the handle, pivot member and connected cam member. As
shown in FIGS. 58-62, the angular orientation of the indicia 910,
or flat portion, provides the user with an indication of the
setting or position of the tilt limiter.
[0120] For example, as shown in FIG. 58, a forward portion 912 of
the indicia is angled downwardly, with a rear portion 914 angled
upwardly, such that the angular orientation of the indicia
substantially mirrors the relative position of the seat, the
rearward tilting of which is being limited to a forward maximum
rearward tilt position. As such, the selector member with its
indicia provides the user with an indication that the tilt limiter
is set at the forward tilt position such that the seat cannot be
tilted rearwardly past the forward tilt position. As explained
below, a forward bias device is actuated to permit the chair to be
tilted into the forward bias position. The forward bias device,
when used in combination with the tilt limiter positioned in the
forward tilt position, allows the user to lock the seat and chair
in the forward bias position such that it cannot be tilted
rearwardly. It should be understood, however, that the forward bias
device can be actuated without the tilt limiter being positioned in
the forward tilt position.
[0121] Referring to FIG. 59, the indicia 910 is in a substantially
horizontal position, which corresponds to the tilt limiter being in
an upright or normal tilt position or setting. Again, the selector
member with its indicia provides the user with an indication of the
tilt limiter setting and informs the user that the seat cannot be
tilted rearwardly past the upright tilt position. Although the seat
is shown in the maximum rearward tilt position for this setting,
which corresponds to the normal or upright tilt position, it should
be understood that the user can tilt the seat forwardly, if
permitted by a proper setting of the forward bias device, without
affecting the position of the selector member or its indicia.
Therefore, the user is apprised of the maximum available tilt
position even when the seat is not located in that position.
[0122] Referring to FIGS. 60 and 61, the forward portion 912 of the
indicia is now angled slightly upward with the rear portion 914
angled slightly downward so as to again mirror the maximum rearward
tilt positions of the seat, which are shown as intermediate tilt
positions. Again, the selector member with its indicia provides the
user with an indication of the tilt limiter setting and informs the
user that the seat cannot be tilted rearwardly past one of the
intermediate tilt positions. As explained above, the selector
member with its indicia performs this notice function even when the
seat is located at some tilt position other than the maximum
rearward tilt position.
[0123] Referring to FIG. 62, the indicia 910 provides the user with
an indication of the tilt limiter setting and informs the user that
the seat can be tilted rearwardly to its maximum reclined
position.
[0124] The selector member with its indicia 910 provides a simple
but ideal way to select the tilt position of the tilt limiter, and
the corresponding maximum rearward tilt position of the seat, while
simultaneously providing the user with an indication of the current
maximum rearward tilt position of the seat The user is informed of
the maximum rearward tilt position of the seat even when the seat
is in a tilt position other than the maximum rearward tilt position
For example, the selector member and tilt limiter can be set to the
reclined position such that the indicia informs the user of that
setting as shown in FIG. 62 The selector with the indicia will
remain in this position even as the user tilts forwardly to any of
a forward, upright or intermediate position so as to continue to
inform the user that he or she can tilt rearwardly to the reclined
position.
[0125] Although the selector member has been shown as a handle, or
knob with the indicia providing a grippable portin of the handle,
it should be understood that that selector member can be configured
as any number of members including for example, but not limited to,
a lever, dial, arm or gear In addition, it should be understood
that the indicia can take many forms other than the integrally
formed and laterally extending raised portion described above For
example, the indicia can be comprised of various numerical or
alphanumeric characters, words or color codes applied to or formed
on a selector member or similar member Similarly, the selector
member can be provided with any number of markings, including, but
not limited to scales, grids and arrows, such that angular rotation
thereof will provide the user with an indication of the
corresponding position of the tilt limiter. The indicia, including
any markings or etchings, can also comprise raised portions,
indentations or applied materials, such as paint, or adhesive
labels.
[0126] Although the preferred embodiment of the selector member
with its grippable indicia has been shown as comprising the handle
used to actuate the tilt limiter, it should be understood that the
selector member can be separate from the handle, or similar
actuator. In such an embodiment, the selector member is linked or
connected to the tilt limiter or actuator so as to provide an
indication of the tilt limiter setting.
[0127] As shown in FIGS. 16-19, a forward bias device 172 is
rotatably mounted to the seat support 20 with a pair of C-shaped
catches 502 and includes a rod 174 and a pair of cam members 176.
The housing includes two pairs of notches 178, 180 shaped to
receive the cam members along a top of each of the sidewalls 62 of
the housing. In operation, as the user tilts rearwardly in the
chair, as shown in FIGS. 16 and 17, the rod 174 is rotated such
that the cam members 176 are pivoted forwardly so as to be
substantially parallel with the seat support. As the user returns
the seat to the upright position, the cam members are received in
the upper notches 178, which define the forward bias position of
the chair. Alternatively, the user can rotate the rod 174 such that
the cam members 176 angle downwardly from the seat support and are
received in the lower notches 180, which define the normal seating
position of the chair.
[0128] Alternatively, a forward bias spacer can be mounted in the
catches 502 as shown in FIGS. 6A and 15. The forward bias spacer
includes an axle 600 connected to a laterally extending spacer
member 604, or flange, with an arm 602 A rear portion of the arm
extends rearwardly of the axle to act as a stop 606 such that the
forward bias spacer cannot rotate about the axis of the axle The
spacer member 604 is positioned between the front wall of the
housing and the bottom of the seat support and maintains the seat
in the upright normal seating position The forward bias spacer
replaces the forward bias device when it is not desirable to have a
chair that can be biased into the forward bias or tilt
position.
[0129] Now referring to FIGS. 32-39, the back support 30 includes a
pair of uprights 200 extending upwardly from the support arms 50. A
lower cross member 202 connects the support arms and an upper cross
member 204 connects the upper portions of the uprights. Preferably,
the back support 30 is one piece and is formed from a single piece
of material. As shown in FIGS. 1 and 3, the back support is
exoskeletal in nature and provides the user with a strong visual of
support, security and durability.
[0130] Each upright 200 is preferably formed as a channel 212 as
shown in FIGS. 32, 35 and 36. Cover members 640 are snap fitted
onto lower portions of the back support to cover the lower portion
of the channel. For example, in one embodiment, a rib extends from
the channel and a corresponding rib extends from the cover so as to
be aligned with the rib of the backsupport. The ribs are connected
with S-shaped clips.
[0131] A rack 206, consisting of a plurality of laterally oriented
notches 208, is formed along an inner portion of the base portion
210 of the channel. As shown in FIGS. 1, 2 and 36, a bar member
220, preferably configured as a cylindrical rod, is installed in
each channel 212 in an overlying relationship with the rack 206 by
mounting opposite ends of the bar to the base portion 210 of the
channel.
[0132] In a preferred embodiment, the upper end 222 of the bar
member is received in a groove 226 while the lower end 224 is
bolted to a lug 228 formed in the channel. Bar member 230,
preferably having a flat rectangular cross-section, is mounted to
the upright in a spaced apart and parallel relationship with bar
member 220 by attaching opposite ends 232, 234 of the bar member to
lug portions 236, 238 formed in the channel 212.
[0133] As shown in FIGS. 36 and 39, opposite ends of bracket 240
are slideably mounted on each bar member 220. As shown in FIG. 1, a
backrest 32, preferably including a cushion and an internal pan
(not shown) is attached to the brackets 240. The backrest 32, and
brackets, slide along the bar members 220 and are releasably
secured to the uprights of the back support with a locking
device.
[0134] In a preferred embodiment, shown in FIG. 36, the bracket
includes an upper vertically oriented slot 242 on each side of the
bracket and a lower slot 244 extending inwardly from the edge of
the bracket and then downwardly along a vertical path. A pawl
member 246 is disposed within the bracket and is pivotally mounted
within the upper slot 242 with a pair of guide members 248. A lower
portion of the pawl member includes an engagement portion 250
adapted to engage the rack 206 and a pair of guide members 252
engaging the lower slot 244. A spring 254 is disposed within the
bracket so as to bias the pawl 246 and engagement member 250 toward
the rack 206. Preferably, either the pawl or the notches of the
rack are tapered with a flat horizontal surface so as to allow the
pawl to pass over the notches without engagement when traveling in
the upward direction.
[0135] In operation, the backrest 32 is raised to a desired
position where the engagement member 250 of the pawl 246 engages
one of the notches in the rack. As the backrest is raised to its
uppermost position, the guide members 252 engage a ramped guide
rail 256 formed in the back support channel 212 The guide rail 256
forces the lower guide members 252 forwardly in the slot 244
against the force of the spring 254 and then downwardly in the slot
244 as the upper guide members 248 are also moved downwardly within
the slot 242 so as to lock the pawl member in a disengaged position
away from the rack. The user can lower the backrest to a lowermost
position wherein a stop member 258 engages the guide members 252 to
move the pawl 246 upwardly within the slots 244, 242 until the
spring 254 biases the pawl forwardly into engagement with the rack,
wherein the backrest can again be raised to the desired position In
this way a simple device is provided for adjusting the backrest
without a multiplicity-of moving parts and levers.
[0136] In an alternative embodiment, the pawl is simply pivotally
connected to the bracket, without the additional slots that allow
for vertical travel The pawl is biased into engagement with the
rack by the spring disposed between the bracket and the pawl A
paddle, similar to the one shown in FIG. 44, extends inwardly from
the pawl so as to be exposed to the user adjacent the upright The
paddle can be actuated by the user in opposition to the spring so
as to disengage the pawl wherein the backrest can be raised or
lowered to the desired position.
[0137] A similar device is shown in FIGS. 44-45. Since this
embodiment of the backrest support structure is similar to
previously described embodiments, similar parts appearing in FIGS.
44 and 45 are represented by the same reference numbers. As shown
in the alternative embodiment of FIGS. 44 and 45, a lever 260
including a handle 262, or paddle, and a nose portion 264 is
pivotally attached to a bracket 266. The handle 262 extends
laterally inward from the upright 200 and is exposed to the user
adjacent the upright. The nose portion 264 engages one of the
notches of the rack. A spring 268 biases the handle 262 and lever
rearwardly to maintain operable engagement between the nose portion
264 and the rack. To adjust the height of the backrest 32, the user
pivots the handles and lever forwardly to disengage the nose
portion from the rack and thereafter slides the backrest to the
desired position In a preferred embodiment, the lever is biased
against the neck with a spring. The lever is then released so that
the nose portion engages the rack once again. Preferably, the nose
portion and cooperating notches in the rack are tapered upwardly
such that the backrest can be moved upwardly without moving the
handle and lever. For upward adjustment, the user simply lifts the
backrest such that the nose portion rides over the notches until
the desired height is reached.
[0138] In yet another alternative embodiment shown in FIGS. 53-55,
the upright includes a longitudinal groove 270. A rack 272 is
formed in the upright adjacent to and in parallel relationship with
the groove A spline member 274 has a base portion 276 and a tongue
member 278 extending rearwardly from the base portion and
terminating in a hook portion 280. The tongue member 278 is
inserted in the groove 270 such that the hook portion 280 engages
an inner track 282 opening into and communicating with the groove.
Once the tongue and hook member are engaged in the groove and
track, a plate member 284 is inserted and snapped into place
between the tongue 278 and a surface of the groove so as to
securely mount the spline 274 to the upright in a sliding
relationship A latch member 286 is installed in a recess 288 formed
in the base portion 276 and includes a inwardly extending lever 290
accessible to the user adjacent the upright. A nose portion 292 of
the latch member engages the notches in the rack. A spring 294 is
installed between the latch member and the backrest, which is
mounted on the base portion, to bias the nose portion into
engagement with the rack. The latch member 286 is retained in the
recess of the base portion by the back portion and spring. In
operation, the backrest can be adjusted as described above. In this
embodiment, the armrests are shown as being fixedly attached to the
housing, but it should be understood that they can be made height
adjustable as explained below.
[0139] Since the backrest is supported on opposite sides of the
chair, it does not need to be structural in nature, and can be made
at less expense and with more tolerance at the interface of the
backrest and uprights. Moreover, the load imparted by a user
against the side of the backrest can be transmitted directly
through the forwardly extending arms of the back support to the
housing and spring member so as to provide better support for the
user. Additionally, the lever for releasably locking the backrest
is preferably located adjacent the uprights at the side of the
chair, and is therefore easily accessed by the user.
[0140] In addition, the backrest 32 covers the channel 212b in the
upright so as to conceal the bar members 220, 230, the backrest
bracket 240 and the armrest base portion 302 having the locking
device disposed therein. In this way, the chair is provided with an
exoskeleton backrest support, but with the sliding and locking
parts concealed from the user so as to provide an aesthetically
pleasing appearance.
[0141] Another feature of the improved chair is the adjustable
armrest 300 shown in FIG. 37, which is slideably mounted on bar
member 230. Each armrest 300 includes a base portion 302 and an arm
portion 304 extending forwardly from the base portion. Preferably,
pads 306 are installed on an intermediate support 307 which are
then mounted on an upper surface of the arm portion A cavity 308 is
formed internally in the base portion. An upper and lower opening
communicate with the cavity and are shaped to receive bar member
230 A locking device 310, including a latch member 312, is disposed
in the cavity and releasably engages a rack 314 consisting of a
plurality of notches formed in a front surface 316 of the bar
member. Preferably, as shown in FIG. 40A, the cavity 308 has front
wall 318 which forms an oblique angle with the front surface 316 of
the bar member which passes through the cavity. Likewise, the latch
member 312 is configured as a wedge-shaped member having opposite
surfaces 322, 324 forming an oblique angle with each other. The
latch member also includes a protuberance 320, or tooth, extending
rearwardly from the rear surface 322.
[0142] In an alternative embodiment shown in FIG. 37A and 40, a cap
700, preferably metal, is mounted to the top of the base portion
with a fastener 702. The base portion includes a raised boss 701 on
which the cap is disposed. The cap has an opening 704 shaped to
receive the bar member. The cap member is preferably formed with a
slightly smaller opening than the upper opening in the base portion
so that the metal cap member absorbs the loading from the arm. The
boss 701 and the fastener 702 then transmit the load into the base
portion of the armrest.
[0143] By providing uprights along opposite sides of the chair, the
armrests can be conveniently attached to the uprights, rather than
being supported by separate supports extending from the base or
housing of the chair. In this way, the armrests can be firmly
attached in a simple way at less cost.
[0144] In operation, the wedge-shaped latch member 312 is disposed
in the cavity such that the rear surface 322 abuts the front
surface 316 of the bar member and such that the protuberance 320 is
received within one of the notches of the rack. The front oblique
surface 324 abuts the front wall of the cavity 318. The latch
member includes a downwardly extending trigger member 820 having an
outwardly extending flange member 338. The wedge shaped latch
member biases or wedges the base portion against the rear surface
326 of the bar member so as to tightly secure the armrest to the
upright and thereby provide a firm support for the user's arm A
guide member 328 is mounted within the cavity in the base portion
and engages a bottom surface 330 of the cavity A spring 332 is
inserted between the guide member 328 and the wedge-shaped latch
member 312 to bias the latch member upwardly against the armrest
and against the bar member.
[0145] As shown in FIG. 37, a lever member 334 is pivotally mounted
to the bottom of the armrest and includes an end 336 operably
engaging an outwardly extending flange 338 of the latch member 312.
Alternatively, as shown in FIG. 37A, a U-shaped clip 810 is
disposed over the lever and engages the armrest to secure the lever
in the armrest such that it pivots about a fulcrum in the armrest.
The lever member preferably includes a cantilevered spring portion
337 that engages a surface in the arm to bias outwardly a button
portion 340 of the lever that is exposed to the user.
[0146] To adjust the armrest, the user pushes end 340 of the lever
member so as to pivot the opposite end 336 while simultaneously
lifting the armrest. In this way, the end 336 of the lever acts on
the flange 338 of the latch member to pull it down against the
force of the spring 332. As the arm is moved relative to the latch
member, the latch member slides along the front wall 318 of the
base portion such that the protuberance, or tooth, disengages from
the rack in the bar member. When the latch member is disengaged,
the user can move the armrest to the desired position. The user can
thereafter release the lever and armrest to reengage the bar member
by engaging the rack with the protuberance or tooth. As with the
backrest, the armrest can be moved upwardly without actuating the
lever, since the upward movement naturally allows the latch member
to disengage from the bar as it slides downwardly within the
cavity.
[0147] As shown in FIG. 43, an alternative embodiment of the
locking device includes a wedge shaped latch member 344 disposed in
the cavity, but without a protuberance or corresponding rack on the
bar member, although it should be understood that such aspects
could be incorporated into the device Parts similar to those
described above are represented by the same reference number for
the sake of simplicity. A spring 332 is disposed in the cavity 308
between a bottom wall 330 of the cavity and a bottom surface 342 of
the latch member. A lever 346 extends upwardly from the wedge
shaped member through the upper opening in the base section so to
be exposed to the user In operation, the user pushes the lever
downwardly against the force of the spring while lifting the
armrest to thereby relieve the frictional forces acting between the
armrest, latch member and bar member. The armrest can then be moved
to the desired position where the lever is then released, the
spring acting on the latch member to force it once again into
frictional engagement between the armrest and bar member. In such
an embodiment, the armrest is provided with infinite adjustment
capability.
[0148] In yet another alternative embodiment shown in FIG. 46, a
rack 348 is formed along a rear surface of the bar member and the
base portion includes a integrally formed nose portion 350 shaped
to be received within the rack. As with the backrest, the nose
portion 350 and rack 348 are preferably tapered in an upward
direction. A spring 352 and button 354 are installed in a top
portion of the base and engage a front surface of the bar member.
Alternatively, it should be understood that a leaf spring could be
substituted for the spring and button. In operation, the user
simply lifts up on the arm portion of the armrest in opposition to
the force of the spring so as to disengage the nose portion. The
armrest is then moved to the desired position and released such
that the nose portion engages a notch in the rack.
[0149] Referring now to FIGS. 47-49, various embodiments of a
locking device are shown as having a rack 356 formed in the base
portion of the upright, again with upwardly tapered notches. The
armrest includes either a nose portion 358 integrally formed in the
base portion, FIG. 48, a first pin 360 attached to the base portion
and engaging the rack and a second pin 362 trapped in a track 364
formed between the bar and the upright channel, FIG. 49, or a latch
member 366 having a nose portion 368, FIG. 47, which engages the
rack. The device of FIG. 48 also includes a button 370 and spring
372 to bias the armrest into engagement Again, it should be
understood that a leaf spring could also work in place of the
button and spring. The device of FIG. 47 includes a button 374
having a wedge shaped surface 376 that engages a cooperating wedge
shaped surface 378 on the latch member 366. The button is actuated
to force the latch member forwardly against the force of a spring
as the wedge shaped surfaces slide over each other and thereby
disengages the nose portion from the rack A similar device is shown
in FIG. 56, but with the rack located on the bar member.
[0150] In yet another alternative embodiment shown in FIG. 50, a
pivot member 380 is pivotally mounted to the base portion of the
armrest. The pivot member includes a nose portion 382 shaped to
engage a rack 384 located on the bar member. A cable 386 is
connected to the pivot member. In operation, the user actuates the
cable to pivot the pivot member into and out of engagement with the
rack. Alternatively, the pivot member can be directly actuated, or
pivoted, by hand without a cable. It is preferable to apply the
lifting force to the armrest adjacent or proximate the bar member
so as to reduce the binding force between the base portion and the
bar member. When applying the lifting force at the forward portion
of the arm distal of the bar member, low friction bearing surfaces
applied to one or more of the armrest and/or bar member can
facilitate the adjustment operation.
[0151] In yet another embodiment shown in FIG. 52, the armrest
includes a pair of pins which ride in a slot 394 formed in the
upright. The upper pin 390 engages a rack 388 formed in the
upright. In operation, the armrest is lifted upwardly to disengage
the upper pin. The armrest is then moved to the desired position
where it is released so that the upper pin once again engages the
rack.
[0152] In yet another embodiment shown in FIG. 51, a laterally
extending pin 396 is mounted to the upright The base portion of the
armrest includes a pivot member 398 having a rack 400 formed in a
rear surface thereof The pivot member 398 is pivoted forwardly
against the biasing force of a spring 402 mounted in the base
portion to release the rack from the pin after which the armrest
can be moved to the desired position. The pivot member is then
released such that the spring 402 biases the pivot member 398 and
rack into engagement with the pin.
[0153] Although a number of alternative embodiments of the locking
mechanism for the armrest have been shown and described, it should
be understood by one of skill in the art that various combinations
of racks, wedges, levers and/or springs not specifically described
herein would also work.
[0154] Although the present invention has been described with
reference to preferred embodiments, those skilled in the art will
recognize that changes may be made in form and detail without
departing from the spirit and scope of the invention. As such, it
is intended that the foregoing detailed description be regarded as
illustrative rather than limiting and that it is the appended
claims, including all equivalents thereof, which are intended to
define the scope of the invention.
* * * * *