WO2000074531A2

WO2000074531A2 - Ergonomic chair

Info

Publication number: WO2000074531A2
Application number: PCT/US2000/015327
Authority: WO
Inventors: Niels Diffrient
Original assignee: Soft/View Computer Products Corp.
Priority date: 1999-06-04
Filing date: 2000-06-02
Publication date: 2000-12-14
Also published as: CA2394954A1; TWI235645B; CA2394954C; WO2000074531A3; AR026126A1; AU5318700A

Abstract

A chair of the tilting type which includes a base (110), a seat (111) and back (112), with the base (110) pivotally supporting the seat (111) with two parallel links (120, 123) of a four-bar parallel linkage, with one of the links extending to support the back. The four-bar linkage is duplicated on each side of the chair by forming the two opposite parallel links or cranks (123) from the upturned ends of the tubes (113) which pass through the base (110) in parallel but vertically offset fashion, the base (110) thus forming the fixed bar of the linkage with its opposite bar or coupler being formed by the seat (111). Also disclosed is an adjustable armrest (600) and a headrest (370) that is pushed into lace when the chair is reclined and retracted.

Description

ERGONOMIC CHAIR

This application is a continuation-in-part of my earlier filed U.S. Patent Applications

Nos. 29/103,157 filed April 9, 1999, 29/103,158 filed April 9, 1999, and 29/103,159 filed April

9, 1999, each of which are hereby incorporated by reference as showing embodiments of my

inventions.

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 ofthe 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 ofthe user and as the tilt

angle is increased. In a yet further preferred embodiment, the chair has a tilting mechanism

which changes the angle ofthe seat and its support and increases the chair's angle of maximum

recline, as well as providing a forward tilting position.

2. Description ofthe 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 ofthe chair back is not coordinated with

the natural body action. This problem can also be accentuated by the tendency ofthe hips ofthe

user to slide forward as the back tilts rearwardly. In chairs where both the seat and back recline as a unit, in the reclined position there is a

tendency to lift the legs ofthe user from the floor creating an undue pressure by the forward edge

ofthe seat against the underside ofthe legs ofthe user immediately above the knee. To overcome

this problem the pivot point ofthe 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 ofthe

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 ofthe 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 ofthe user to provide a restoring force to return the chair

back to an upright position after a user has reclined in the chair. 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 ofthe 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 ofthe

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. OBJECTS OF THE INVENTION

It is an object of one embodiment ofthe 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 ofthe seat and back.

An alternative object is to provide armrests that are readily adjusted.

These and other objects and advantages ofthe invention will become apparent as the

following description proceeds.

To the accomplishment ofthe 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 ofthe various ways in which the

principles ofthe invention may be employed.

SUMMARY OF THE INVENTION

Among advantages, some embodiments ofthe 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 ofthe 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 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 ofthe chair, and the relationship of

the components, is such that as the back is reclined the entire seat raises against the weight ofthe

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 ofthe 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 ofthe seat

rear region against the occupant's weight. The combination ofthe upward movement ofthe chair

seat in conjunction with the reclining rotation ofthe chair back simulates the movement ofthe

user's torso about the user's hip joint as the user reclines.

Some other embodiments ofthe 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 ofthe 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 ofthe reclining body. 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 ofthe

way position when not needed.

In still further embodiments ofthe 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 armrests 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

ofthe 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 ofthe 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 ofthe opposite links on each side ofthe chair extends to support the

back. Additionally reclining chair embodiments ofthe present invention usually have a base

that forms a fixed bar ofthe linkage. This linkage translates the actuation ofthe rear links into a

change in the angle ofthe forward links.

Some ofthe reclining chairs ofthe present invention have a spring in the base which acts

on one ofthe bars ofthe 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 ofthe present invention is not

normally noticed by the user, nor does such a chair lift the user's feet off of the floor. 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 ofthe back to

increase the angle ofthe user's torso to his legs.

This reclining ofthe seat and back can be achieved with a four-bar linkage. The four-bar

linkage can be parallel or non-parallel. In one embodiment ofthe inventive chair, the seat is

supported on each side by one ofthe links or cranks ofthe four-bar linkage. The base ofthe

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 ofthe base to the forward portion ofthe seat.

The linkage is duplicated on each side ofthe chair.

The pivots ofthe linkage are designed so that the body weight tends to balance the seat

pivot and a spring within the base is operative on one ofthe bars ofthe linkage to urge the chair

to an upright position, simply to overcome the weight ofthe 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 ofthe 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 ofthe present invention uses the body weight ofthe 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 ofthe seat and back. 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 ofthe 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 ofthe seat and the front

portion ofthe back are typically contour molded and covered by a conventional cushioning

material.

The underside ofthe seat front region (typically at the front ofthe rails that support the

seat pan or support) is connected to the base by a pivot, and the underside ofthe seat rear portion

is connected via a link to the lower region ofthe back.

As the seat reclines, and the rearward links (typically extensions ofthe back support)

pivot about the rear pivot points on the chair base. As a result ofthe this pivoting, the pivot

points under the seat support are raised slightly upwardly and rearwardly. The action ofthe 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 ofthe seat. This lifting ofthe 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 ofthe

invention has a substantially uniform resistance to reclining due to the fact that it is the occupant's weight which produces such resistance. As the reclining tension is adjusted by the

weight ofthe occupant, the greater the occupant's weight, the greater the force required to recline

the seat back, and vice versa.

In some embodiments ofthe 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 ofthe

chair. Preferably, the adjustable arm support rods originate from an "exoskeleton" that holds the

back ofthe chair. While it is most preferred that the chair having the adjustable arms is the

reclinable chair of this application, the adjustable arms ofthe 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 ofthe 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

ofthe 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 occupant's head is aligned with the occupant's back, the support is moved out ofthe way. It is

preferred that the headrest moves on an arc that mimics the natural movement ofthe 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 ofthe 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 ofthe 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

tilted position; 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 ofthe 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 ofthe 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; 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 ofthe present invention;

FIG. 20A shows a cut away view ofthe headrest mechanism of FIG 20 taken along line

20A-20A;

FIG. 20B shows a cut away view ofthe headrest mechanism of FIG 20 taken along line

20B-20B;

FIG. 20C shows a cut away view ofthe 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 ofthe 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 ofthe present invention;

FIG. 22 shows a view of an exploded view of an automatically adjustable headrest; FIG. 23 is a side cutaway view showing an embodiment of a supplemental backrest

adjustment mechanism;

FIG. 23 A is an exploded view ofthe 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 ofthe inventive chair incorporating the

inventive armrest and the inventive headrest;

FIG. 34A is a sectional view ofthe back ofthe chair of FIG. 34 taken along line 34A-34A

in FIG. 34; and

FIG. 34B is a sectional view ofthe back ofthe 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 the present invention for reclining the back of a chair can be used alone, or it could be used with

the method and mechanism ofthe adjustable armrest, the method and mechanism ofthe

adjustable headrest and/or the method and mechanism of the tilt mechanism. FIG. 34 illustrates

a chair that incorporates several aspects ofthe present invention into a chair design specifically

including the method and mechanism ofthe present invention for reclining the back of a chair,

adjustable headrest and the method and mechanism ofthe 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 ofthe

seat in a way that uses the seat occupant's weight to counteract the reclining force is described.

Thereafter, other inventive aspects ofthe 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 ofthe 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 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 11 1 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 ofthe 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 ofthe back

support 124 is not the chair occupant's hip joint. Consequently, the recline ofthe back

circumscribes an arc that is displaced from the arc based on the user's hip joint. However, the concurrent action ofthe 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 ofthe 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 1 11 has a layer of a non-compressible, displacing gel. For

example, a polyurethane gel is useful. Typically the gel pad on seat 1 11 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 111 is shaped to reduce pressure points at the thickest portion ofthe gel.

Typically the back 112 has an about ³A inch thick layer of a conventional soft foam

attached to the rigid shell.

FIG. 21 provides another view ofthe interaction ofthe parts ofthe 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 1 10 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 1 19 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. Also shown in FIG. 21 is a plurality of slots that permit the seat ofthe 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. 21 A 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 111.

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 ofthe 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 ofthe 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 ofthe chair. Base 1 10 has a forward

pivot axis 121 and a rearward pivot axis 124. In the reclining chair ofthe present invention, the

pivot axes are connected to two links ofthe four-bar linkage that interconnects the reclining of the chair back with a raising ofthe 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 ofthe chair back into a forward motion ofthe headrest.

In an alternative, preferred embodiment ofthe 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 ofthe chair above base 1 10 and all parts attached to top

320.

FIG. 8 shows a side view of base 1 10 in the forward tilted position. In this view, base

housing top 320 is substantially horizontal. Base housing top 320 is pivotally connected to base 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 ofthe 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 110.

In a preferred embodiment ofthe 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. 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

ofthe tilt of spring 125 from the vertical plane increases and decreases as the angle ofthe 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 ofthe 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 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 ofthe additional tilt mechanism ofthe 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 ofthe 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 ofthe 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. 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 ofthe 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 ofthe 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 ofthe present invention, the chair is provided with a headrest that is

urged forward as the back ofthe 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 ofthe user and the

automatically adjusting headrest developments ofthe present invention is illustrated by FIGs. 3

and 4. Specifically, in addition to the several elements discussed in connection with the reclining

mechanism ofthe 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 ofthe headrest

370 relative to mounting 390. For example, vertical adjustment 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 ofthe 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 has a centerpoint corresponding to an imaginary axis through the shoulder joint ofthe user and a

radius corresponding to the distance from this centerpoint to the bottom ofthe 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

ofthe chair into the position where it provides the head ofthe 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 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 ofthe 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 ofthe present invention is a mechanism for fixing the position ofthe

adjustable arms which can be used in any chair, including the reclining chair ofthe present

invention. FIGs. 11 and 12 illustrate a preferred embodiment ofthe mechanism for fixing the

position ofthe 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 ofthe arm can be readily changed.

More particularly, FIG. 11 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 ofthe 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. When terminal end 610 of armrest 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 ofthe ratchet faces with the complementary ratchet teeth, the

reverse side ofthe 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 ofthe chair about 6 to 12 inches above

the rear portion ofthe 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 ofthe chair. When the arms are not

interconnected, the shape ofthe 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 ofthe seat (if the armrests

incorporate the horizontal adjustment development ofthe present invention, then the armrests

should be substantially parallel to the sides ofthe seat when the armrests are in a centered

position) and (ii) not interfere with the user sitting back in the chair. 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 ofthe armrest ofthe present invention.

This patent is hereby incorporated by reference.

FIGs. 13 and 14 illustrate an alternative embodiment ofthe mechanism for fixing the

position ofthe 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 ofthe mechanism for fixing the position ofthe 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 ofthe mechanism for fixing the position ofthe 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 ofthe 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. 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 ofthe 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 ofthe 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 ofthe other when the connecting bar

is disengaged.

FIG. 23 shows yet a still further aspect ofthe present invention that can be incorporated

into the reclining chair ofthe 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 ofthe track 900 and carriage 910 mechanism,

carriage 910 also has a conventional pivot mechanism that permits seat back 1 12 to rotate

somewhat about this pivot and provide a further adjustment to better support the chair occupant. Such an embodiment is illustrated in FIG. 23 A. 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 returned 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 ofthe carriages on the track. Additionally, it is also desirable that such tracks

have stops on each end ofthe track to prevent the carriage from traveling beyond the end ofthe

tracks. By putting seat 111 on such a track mechanism₁ the user is provided with yet another

means of ensuring that the seat conforms the geometry ofthe user's body, and not vice versa.

A further development in armrests that can be incorporated into the adjustable

armrests ofthe present invention, or into conventional armrests is a mechanism to permit pivotal

horizontal repositioning ofthe 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 ofthe 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 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 ofthe 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. 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 ofthe user's thumb on one side and the user's fingers on the other so that the user can

readily adjust the pivot position ofthe 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.

Claims

What I claim is:

1. A chair comprising:

a) a chair pedestal;

b) a base mounted on said chair pedestal;

c) a back pivotally attached to said base on two sides;

d) said back having an extension beyond said pivot point on each side of attachment;

e) a pair of front legs pivotally attached to each side of said base to which said back

is attached; and

f) a seat pivotally attached to said front legs and said back extensions.

2. The seat of claim 1 in which said front legs each form a forward facing angle of at least

about 5° with the plane ofthe top of said base.

3. The seat of claim 1 further comprising an adjustable armrest.

4. A reclining chair comprising:

a) a chair pedestal;

b) a base mounted on said chair pedestal;

c) a seat and a reclining back pivotally mounted to said base;

d) a substantially horizontal rearwardly projecting arm mounted to a member ofthe

group consisting ofthe chair pedestal, the base and the seat;

e) a track extending in an arcuate path from said back;

f) a carriage movably mounted on said track;

g) a rod connecting said projecting arm and said carriage; and

h) a headrest mounted on the end of said carriage furthest from said seat.

5. The chair of claim 4 further comprising an adjustable armrest.

6. The chair of claim 4 in which said pivotal mounting of said seat and back comprises an

extension of said back extending from a pivot point on said base to a support for said seat, which

extension forms a forward facing angle of at least about 5° with the plane ofthe top of said base.

7. The chair of claim 6 further comprising a pair of front legs pivotally connected to the

front of said base and the front of said seat support and forming a forward facing angle of at least

about 5° with the plane ofthe top of said base.

8. A headrest subassembly for use in a chair with a reclinable back, said headrest

subassembly comprising:

a) a headrest having a vertical mounting bar;

b) a headset mounting bracket attached to the vertical mounting bar of said headset

and slidable attached to a guide rail affixed to the back f said chair; and

c) a rod adapted to be attached to the chair.

9. A chair comprising:

a) a chair base;

b) a seat attached to said chair base;

c) a back attached to said chair;

d) a substantially C shaped upper rod wherein the approximate center of said

substantially "C" shaped upper rod is attached to the back of said back;

e) a substantially C shaped lower rod wherein the approximate center of said

substantially "C" shaped lower rod is attached to the back of said back below the point where

said substantially "C" shaped upper rod is attached to the back of said back;

J f) a left armrest attached to said substantially "C" shaped upper rod and said

substantially "C" shaped lower rod near the end of said rods on the left side of said chair; and

g) a right armrest attached the said substantially "C" shaped upper rod and said

substantially "C" shaped lower rod near the end of said rods on the right side of said chair.

10. The chair of claim 9 further comprising:

a back-arm interface positioned behind said chair back about 6 to 12 inches higher than

said seat, said back-arm interface having a first aperture adapted to receive said substantially "C"

shaped upper rod and a second aperture adapted to receive said substantially "C" shaped lower

rod.

11. The chair of claim 9 further comprising:

in said back-arm interface a mechanism for fixing the position of said armrests.

12. The chair of claim 11 in which said mechanism for fixing the position of said armrests is

disengaged by raising the distal end of said armrest and is re-engaged by releasing said armrest.

13. A chair comprising :

a) a chair base;

b) a seat attached to said chair base;

c) a back attached to said chair;

d) an approximately quarter circle shaped upper rod wherein the approximate center

of said approximately quarter circle shaped upper rod is attached to the back of said back;

e) an approximately quarter circle shaped lower rod wherein the approximate center

of said approximately quarter circle shaped lower rod is attached to the back of said back below

the point where said approximately quarter circle shaped upper rod is attached to the back of said

back; and f) an armrest attached to said approximately quarter circle shaped upper rod and said

approximately quarter circle shaped lower rod near the end of said rods.

14. The chair of claim 14 further comprising

said seat, said back-arm interface having a first aperture adapted to receive said approximately

quarter circle shaped upper rod and a second aperture adapted to receive said approximately

quarter circle shaped lower rod.

15. The chair of claim 14 further comprising :

in said back-arm interface a mechanism for fixing the position of said armrest.

16. The chair of claim 14 in which said mechanism for fixing the position of said armrest

comprises a ratchet face and a ratchet surface.

17. The chair of claim 14 in which said mechanism for fixing the position of said armrest

comprises a plurality of ratchet faces and ratchet surfaces.

18. An armrest pivotable in a horizontal plane comprising

a) a bracket adapted to be attached to an armrest support arm;

b) a vertical pivot axis attached to said bracket;

c) an armrest support rotatably attached to said vertical pivot axis; and

d) a mechanism for securing said armrest in a fixed position in the horizontal plane

of movement.

19. A chair having a tiltable back comprising:

a) a base supporting a seat support;

b) a seat mounted on said seat support; c) a seat back rotatably attached to said seat; and

d) a headrest slidably attached to said seat back in a manner effect to move said

headrest forward when said seat back moves backward.

20. A chair having a tiltable back comprising;

a) a base supporting a seat support;

b) a seat mounted on said seat support; and

c) a seat back rotatably attached to said seat;

wherein said seat support comprises a spring mechanism effective to provide a resistance to

rotating said seat back that increases as said seat back is rotated from its resting position.

21. A method of using a chair comprising:

a) reclining the back ofthe chair;

b) concurrently with said reclining of said back, raising and moving backward the

seat of said chair; and

c) using the force generated by said seat raising to return said back to an upright

position.

22. The method of claim 21 in which said seat is raised at an acute angle of at least 5° from a

horizontal axis.

23. The method of claim 21 in which a predetermined point on said seat is raised in an

arcuate path provided the resting position of said predetermined point is elevated at least 5° on

said arcuate path from the axis of a substantially horizontal base of said chair.

24. A method of adjusting the vertical position of an armrest comprising the steps of:

a) raising the distal end ofthe armrest to an altitude greater than the altitude ofthe

medial end of said armrest;

b) repositioning said armrest; and

c) releasing said distal end in a manner effective to return said distal end to an

altitude substantially the same as said medial end of said armrest.

25. A method of adjusting the vertical position of an armrest comprising the steps of:

a) positioning said armrest; and

b) releasing said armrest in a manner effective to engage a locking mechanism that

holds said armrest in the position it was placed.

26. A method of adjusting the position of a headrest attached to a chair comprising the step

of:

a) reclining the back of said chair;

b) translating said reclining motion into an upward force;

c) using said upward force to move said headrest into position.

27. The method of claim 26 further comprising the steps of:

a) returning the back of said chair to an upright position;

b) translating said returning motion into a downward force;

c) using said downward force to retract said headrest.

28. A method of adjusting the position of a headrest attached to a chair comprising the step

of:

a) reclining the back of said chair; and

b) concurrently moving the headrest in an arcuate path corresponding to an arc with

a center at the chair occupant's shoulder and a radius corresponding to the distance between the

occupant's shoulder and his ear.

29. A method of altering the return force exerted by a spring in a reclining chair having a

pivot point for said recline and a point at which said spring applies its force comprising the step

of:

a) changing the distance between the pivot point ofthe reclining chair and the point

at which said spring applies its return force.

30. The method of claim 29 in which said return force is increased by increasing said

distance between the pivot point ofthe reclining chair and the point at which said spring applies

its return force.

31. The method of claim 29 in which said distance between the pivot point ofthe reclining

chair and the point at which said spring applies its return force is increased by tilting said spring

rearwardly from said pivot point.

32. A method of using a chair comprising:

a) reclining the back ofthe chair;

seat of said chair, said backward motion beginning with the beginning of said raising motion;

and c) using the force generated by said seat raising to return said back to an upright

position.