US3427072A - Reclining dental chair - Google Patents

Description

Feb. 11, 1969 D. H. HALE RECLINING DENTAL CHAIR Sheet Filed Aug. 15, 1966 Nah Feb. 11, 1969 HALE 3,427,072

HECLINING DENTAL CHAIR Filed Aug. 15, 1966 INVENTQR DEAN H. HALE United States Patent Ofi 3,427,072 Patented Feb. 11, 1969 ice 3,427,072 RECLINING DENTAL CHAIR Dean Howard Hale, 2500 N. Main, Logan, Utah 84321 Filed Aug. 15, 1966, Ser. No. 572,281 US. Cl. 297--342 4 Claims Int. Cl. A47c l /032; A61g /00 ABSTRACT OF THE DISCLOSURE A reclining dental chair apparatus and method, the apparatus featuring a chair seat and back pivotally joined together and supported by a base, (a) the seat being power-driven to move rectilinearly to the base and simultaneously pivot the back relative to the seat by force provided by the same power source, or (b) the back being power-driven to pivot relative to the seat and simultaneously shift the seat oppositely and rectilinearly relative to the base by force delivered from the same power source. The disclosed methods comprise positioning a reclining dental chair so that the disposition of the patients head remains within essentially one predetermined and relatively narrow vertical corridor though occupying any one of a plurality of relatively erect or reclined positions by displacing the seat relative to the base and simultaneously oppositely pivoting the back relative to the seat or vice versa.

The present invention relates to improved dental and like reclining chairs and more particularly to such chairs having improved position control features (a) for easily maintaining the patients head within a convenient work region regardless of whether the chair is fully erect, fully reclined or at an intermediate position and (b) for automatically varying the horizontal location of the center of gravity of the entire chair, including the occupant, relative to the base to compensate for oppositely varying the center of gravity of the patient in the chair responsive to reclining or erecting the chair.

In the reclining dental chair and like arts, as presently constituted, it has become almost a medical necessity, for purposes of time, accuracy and convenience, that the position of the patients head at all times be essentially kept within a single, readily accessible work area, having close horizontal limits, without regard to whether or not the patient is upright or reclined. This enables placement of dental equipment, instruments, tools, materials, etc., in handy proximity, accommodates easy direct-vision illumination at the Work site and accommodates direct, eflicient and accurate work by the dentist upon any region of the oral cavity without the need for mirrors, etc.

Prior known reclining dental chair proposals for maintaining the occupants head within such a work area have been disadvantageous to use, requiring careful, manually coordinated actuation of several position controls by the dentist to (a) recline the patient, in whole or in part, by pivoting the back of the chair relative to the seat of the chair and (b) to return the patients head to the requisite position between the mentioned close horizontal limits. For example, see United States Patent 3,150,898. Also, some commercial adaptations of such prior proposed reclining chairs have, for positioning purposes, required that the base which supports the chair be materially offset from the center of gravity of the chair. Consequently, such chairs require an undue amount of floor space in the dentists ofiice and are economically burdensome because of the support and power actuating equipment must be constructed of especially heavy and/or strong materials to handle such offset loads.

The present invention novelly overcomes the abovementioned objectionable features of the prior art by providing a reclining dental and like chair having improved position control features accommodating synchronous (a) reclining of the back of the chair and (b) automatic advancing of the entire chair relative to the base an adequate distance to compensate in forward motion of the chair for rearward motion of the back to keep the patients head within the prescribed horizontal limits, and vice versa. Thus, the center of gravity of the patientsupporting chair is uniquely and automatically repositioned each time the reclining position of the patient (along with the patients center of gravity) is oppositely changed, without manipulation of multiple position controls.

The presently preferred embodiment of this invention comprises a fluid or comparable motor interposed between the reclining chair and a fixed anchor position, such as at the support base. Either (a) the back of the chair is powered by the motor for pivoting the back relative to the seat with a component of force, created by such pivoting, oppositely, though essentially rectilinearly shifting the entire chair relative to the base or (b) the seat of the chair is powered by the motor for essentially rectilinear displacement relative to the base with a component of force, created by such essentially rectilinear displacement, oppositely, though pivotal relocating the back of the chair relative to the seat. Thus, by singly controlling the one motor, the dentist may recline or erect the patient as desired without displacing the patients head out of the work area beyond the horizontal limits. A second motor is used to locate the entire chair at a suitable working elevation,

With the foregoing in mind, it is a primary object of this invention to provide a novel dental and like chair system, including method and apparatus, having improved position control features accommodating accurate and convenient position regulation of the chair by the dentist.

Another significant object of this invention is the provision of a novel dental and like chair system wherein the center of gravity of the chair is automatically relocated to favorably reposition the chair relative to its supporting base each time the patient is reclined or erected, in whole or in part.

These and other objects and features of the present invention will become more fully apparent from the following description and appended claims taken in conjunction with the accompanying drawings wherein;

FIGURE 1 is a schematic side elevation, partly broken away for clarity, of the presently preferred embodiment of this invention illustrating several positions in which the chair may be disposed by actuation of a single motor;

FIGURE 2 is a fragmentary plan view taken along line 2-2 of FIGURE 1 of the motor and actuating linkage of the chair of FIGURE 1 which linkage causes the back of the chair to be automatically pivotally repositioned each time the position of the chair is rectilinearly altered relative to the base by actuation of the motor;

FIGURE 3 is a fragmentary cross-section taken along line 3-3 of FIGURE 1;

FIGURE 4 is a schematic side elevation of the second presently preferred embodiment of this invention, with parts omitted for clarity; and

FIGURE 5 is a fragmentary plan view taken along line 55 of FIGURE 4 of the motor and actuating linkage of the chair of FIGURE 4, which linkage causes the chair to be automatically rectilinearly repositioned relative to the base each time the pivotal position of the back of the chair is altered by actuation of the motor.

Reference is now made to the drawings wherein like numerals are used to designate like parts throughout. FIGURE 1 depicts a presently preferred reclining dental chair embodiment of the present invention, generally designated 10, adapted to situate a patient, generally designated 12, in any one of a plurality of variously reclined positions, as illustrated in FIGURE 1. Broadly, the chair has for its purpose the maintaining of the patients head 14 Within close horizontal limits so that the dentists instruments, tools, equipment, and materials may be situated in close proximity to such a work area, the mentioned horizontal limits being indicated by the position of the patients head 14 shown in solid lines and the lowest, fully reclined position of the patients head shown at the left in dotted lines. The dotted head position shown to the right of the solid position is a manually-erected position quickly attained when the patient is choking or desires to express liquid from his mouth and is not a dental working position. In this way, the dentist may, with a minimum of time and inconvenience and with accuracy, complete his Work.

Structurally, the chair 10 of FIGURE 1 comprises a reclining back, generally designated 16, comprising a suitable rigid frame 18 including support members running coextensive with the back and designated 20 and transversely-extending cross members, including support member 22 which is rectangular in cross-section and disposed at the bottom of back 16 and near the pivotal connection 24 between the back 16 and a seat 26 of the chair 10. The back 16 preferably is suitably padded and upholstered at the exterior 28, the type and nature of upholstery forming no part of the present invention.

The seat 26 of the chair also preferably comprises a suitable type of exterior upholstery 30 and further comprises a rigid frame 32. The rigid frame comprises a plurality of cambered members 34 extending generally coextensive with the seat 26 as well as the plurality of cross braces 36 integrally joined, such as by welding or the like, to the cambered members 34. Thus, the frame 32 is an essentially rigid frame so that the patient 12 is firmly supported thereby and the frame will move unitarily to and fro across the base, which supports the chair, for purposes and in a manner subsequently to be explained.

A pair of depending hanger members 38 are integrally joined to the frame 32, as for example by welding, and integrally carry a track 40 (FIGURE 3) at one side near the lower end, suitably secured by welding or the like. One such track is located at each side of the chair. Each track 40 is rectangular in cross-section and, therefore, provides an essentially flat top surface 42 and an essentially flat bottom surface 44. The ends of both the left track and the right track are respectively integrally joined as for example, by welding, to the forward cross brace 36 and the rear cross brace 36 so that each track 40 integrally forms part of the seat frame 32 and moves to and fro with the seat frame.

Also, the rear cross brace 36 at both sides, is integrally joined to a pivotable lug 46 which in turn is pin-joined at 48 to lug 50, lug 50 being integral with the back frame 18. Thus, the back 16 is pivotally joined at 48 on each side of the chair to the seat 26 so that the patient 12 can be situated anywhere between a fully erected seated position and a fully reclined substantially horizontal position.

A skirt 52 may be disposed along each side of the seat 26 for appearance and protection purposes thereby concealing the structural and working parts disposed in beneath the seat 26.

The chair 10 is supported by floor-engaging base, generally designated 60 with the relative horizontal positions of the chair and the base preferably being such as to place the center of gravity of the chair, as near as practicable, in vertical alignment with the base no matter to what degree the patient is reclined. Of course, if desired, the base '60 could be otherwise disposed relative to the chair.

The base 60 comprises a covering 62 adapted to conceal from view and enclose a fluid motor, generally designated 64, comprising a cylinder 66 and a ram or piston rod 68. The sole purpose of the motor 64 is to situate the entire chair 10 vertically at a suitable work elevation. A control lever 70 is used in conjunction with a suitable conventional hydraulic system (not shown) to selectively actuate the fluid motor 64.

As best seen in FIGURE 3, the piston rod 68 of the fluid motor 64 is integrally joined to a base plate 72 from which a pair of right and left roller support plates 74 integrally depend. It is to be appreciated that while the base plate 72 is illustrated as being disposed in a substantially horizontally extending orientation, the orientation could be inclined with respect to the horizontal so that the chair 10 would be displaced essentially rectilinearly in the direction of such orientation across the base 60 as the inclination of the back 16 is modified, as will subsequently become better understood.

Each depending roller support plate 74 carries a plurality of combined top and bottom roller assemblies, gene-rally designated and 82, respectively, at each side. Two of each such combined roller assemblies are illustrated as being situated along both the rig-ht and left hand sides of the chair. Apart from location, the idler roller assemblies 80 and 82 are identical and therefore only one will be explained.

The roller assemblies 80 and 82 each comprise a commercially available roller 84, the circumferential surface 86 being in contiguous friction-bearing relationship with the respective surfaces 42 and 44 of the track member 40. The roller 84 is joined by means of a suitable bearing (not shown) to a short shaft 88 which passes through an aperture 90 suitably located in the adjacent depending roller support plate 74. The interior terminal end of the short shaft 8 8 is threaded at 92 and threadedly receives a nut 94 which is secured in its tightened position by a lock washer 96. A spacer 100, interposed between the plate 74 and the bearing (not shown) of each roller 84 maintains the roller surface 84 in proper alignment with the track 40. A nylon or other suitable longitudinally extending guideblock 102, secured to the adjacent plate 74 by means of countersunk bolt assemblies '104 passing through an aperture 106 in the plate 74, also accommodates aligned displacement of the seat 26 relative to the base 60. Thus, the top and bottom roller assemblies 80 and 82 accommodate fore and aft displacement of the chair 10 across the base, the track 40 being lineanly displaced through the top and bottom rollers at such time to create opposite rotation of the idler rollers 84 of the assemblies 80 and 82. Thus, the present construction avoids any need for pivotal connection between the base and the chair.

A position-controlling hydraulic motor, generally designated 120, is interposed between the base plate 72 and the seat frame 32 (FIGURE 1) for the purpose of displacing the chair relative to the base when it is desired to reposition the degree of patient recline. The full stroke of the piston of motor determines the forward and rear extreme positions of the chair with respect to the base. More specifically, the fluid motor 120 comprises a cylinder 122 from which a piston rod 124 extends. The base of a cylinder 122 at integral anchor the lugs being integrally joined to the base plate 72, as for example by welding. Thus, the cylinder 122,

is held in an essentially stationary position by such union with the base plate 72.

On the other hand, the piston rod 124 is pivotally joined at pin 132 to a link 134, which link is integrally joined to the seat frame 32 at the rear cross member 36. The cylinder 122 is a two-way cylinder of con- .ventional type accommodating both forward and rearward displacement under control of the dentist using suitable means including a satisfactory conventional hydraulic system (not shown) and a control lever (not show-n) or the like in a manner generally well known in the art.

A linkage system, generally designated 140, is interposed between the back 16 and seat 26 of the chair and anchored to the base 60 for the purpose of pivoting the back 16 relative to the seat 26 in response to and to an extent commensurate with the magnitude of any rectilinear displacement of the seat across base 60 caused by actuation of the fluid motor 126 through either extending o-r retracting the piston rod 124.

tl he linkage mechanism 140 (best seen in FIGURES l and 2) comprises a link 142, integrally and rigidly depending from the frame 18 of the back 16 at the lower cross member 22, and a telescopic member 144 comprising an outer hollow tube 146 and an inner rod 148, the rod being disposed within the hollow of the tube. The left end of the telescopic tube 146 is pivotally joined, using clevis and a pin 150, to the link 142 and the right end of the rod 148 is joined, to a diagonal link 158 at swivel connection 160. If desired, a one-piece member may be used in place of the two-piece telescopic member 144.

The diagonal link 158 by means of an end connection 164, is rotatably secured near the mid point thereof to a support block 162, which block is integral with the frame 32. The other end of the diagonal link 158 of the linkage system 140 is pivotally joined at pin 166 to a link 170 which extends generally parallel to the telescopic member 144 but is situated at the opposite side of the chair. The rearward end of the link 170 is pivotally joined at pin 172 to an anchor bracket 74, which bracket is suit-ably integrally secured to the base 60 so at all times to be situated in a stationary position.

with the foregoing in mind, the operation of the chair 1!), as illustrated in FIGURES 1, 2, and 3, will now be described. It is to be appreciated that the patient 12 may be reclined or erected in any one of an infinite number of positions between the fully erected and the fully reclined positions, the fully erect position being illustrated with the patients head shown in solid lines at 190 (FIGURE 1) and the fully reclined position being illustrated in dotted lines at 192. These intermediately reclined head positions are also illustrated at 1'94, 196 and 198. It is also to be appreciated that as the fluid motor 120, under control of the dentist, powers the seat 26 to and fro as desired rectil-inearly across the base in a direction defined by the orientation of the base plate 72, a component of force caused by such rectilinear displacement will be transmitted through the linkage system 140 to pivotal ly relocate the back of the chair relative to the seat an amount proportional to the rectilinear distance traversed. Thus, by singly controlling the one fluid motor 120, the dentist may synchronously displace the seat 26 along with the back 16 forward relative to the base 60 and at the same time and under power of the same motor, through the linkage system 140 as accommodated by the counterclockwise moment exerted by the patient upon the back 16, recline the back 16 a cor-responding amount. Where a one-piece memher is used in place of the two-piece telescopic member, the moment exerted by the patient upon the back is irrelevant when reclining or erecting the back.

Likewise, when under control of the dentist, the fluid motor 120 powers the seat 26 back, or to the left as viewed in FIGURE 1, relative to the base 60, the same power provided by such actuation of the motor 120 will displace the linkage system 140 causing the back '16 to be erected a distance proportional to such rear rectilinear displacement of the seat. Hence, the center of gravity of the chair, with patient residing therein, will be automat-ica-lly relocated in a favorable and easily supported reposition with respect to the base '60 each time the patient is reclined or erected, in whole or in part, in the opposite direction. Therefore, the offset distance between the force of the combined center of gravity of the chair and patient and the reaction force exerted by the base 60 will be minimal at all times.

More specifically, when the dentist actuates' the fluid motor so as to displace the chair 26 toward the right relative to the base 60 sufficient to bring the pivotal connection 40, from the solid position 200 to the dotted position 202, the right edge of the seat 26 will be displaced from the position 294 to the position 206 (FIGURE 1), the swivel connection 160 will be displaced from the position 208 to the position 210 (FIGURES 1 and 2), the central pin connection 164 of link 158 (FIGURE 2) will be displaced by movement of the seat 26 from the position 212 to the position 214, the pivotal connection 166 will be displaced from the position 216 to the position 218 (FIGURE 2), and the pivotal connection (FIGURE 1) will be displaced from the position 220 to the position 222.

The mentioned displacement of the connection 150 from the position 220 and to position 222 will cause counterclockwise rotation of the link 142 about pin connection 48, as viewed in FIGURE 1, reclining the back 16 from the position 224 to position 226 and altering the head 14 of the patient 12 from 190 to 194 (FIGURE 1), thereby retaining the head 14 of the patient within close horizontal limits so that the dentist may conveniently and accurately work on any region of the oral cavity Without relocating his tools, instruments, materials and the like and without appreciable inconvenience or loss of time.

In like manner, the fluid motor may be actuated to advance the seat 26 rectilinearly within its limits of operation to any desired position and to correspondingly recline the seat 16, as, for example, by causing displacement of the pivot connection 48 to any of the positions 230, 232, and 234, and, accordingly, causing the right front edge of the seat 26 to be situated at positions 236, 238, and 240, respectively; relocating the swivel connection at positions 242, 244, and 246, respectively; disposing the central joint 164 at the positions 248, 250 and 252, respectively; displacing the pivotal connection 166 serially to the positions 254, 256, and 258, respectively; correspondingly displacing the pivotal connection 150 to the positions 260, 262, and 264, respectively. Such combined displacement will rotate the link 142 counterclockwise about pin connection 48 repositioning the back 16 at the pivoted locations 266 and 268 and 270, respectively. This will correspondingly dispose the patients head 14 at the positions 196, 198, and 192, respectively.

The same procedure may be followed in reverse with opposite actuation of the motor 120, under control of the dentist, to selectively erect the back 16.

Occasionally, for example, when a patient is choking, it is desirable to quickly move the patient from a reclined to a fully erected position. This can readily be accommodated because the telescopic member 144 enables free upward pivotal movement of the back 16 relative to the seat 26 while the seat 26 remains generally stationary. Thus, the dentist need only manually grasp the underside of the back 16 and manually lift the back. This will pivotally displace the back 16 around pin 48 and cause the members 146 and 148 to extend telescopically. Therefore, for example, when the back 16 of the chair is disposed in the fully reclined position 270 (FIGURE 1) and the patients head 14 is located in the position 192, and the patient is choking, the dentist may manually lift the back 16 pivoting the back relative to the essentially stationary seat into the erect position designated 272 in FIGURE 1 thereby placing the patients head in position 274. Thereafter, the patient may again be reclined, the dentist merely releasing his manual support of the back 16 allowing the member 148 to inwardly telescope into the hollow cavity of the member 146, air escaping from the cavity through a suitably sized aperture (not shown) located at the end of the member 146 near the pivot pin 150.

Reference is now made to FIGURES 4 and 5 which depict a second presently preferred embodiment of the present invention. Much of the structure previously explained in conjunction with chair 10 of FIGURES 1-3 may also comprise part of the chair, generally designated 300, of

7 FIGURES 45, and such corresponding structure will not again be described. For example, the base (including the frame and the roller assemblies), the back, the seat, and the pivotal connection between the seat and the back may be the same in each chair embodiment.

Fundamentally, the chair 300 differs from the chair 10 in that the back of the chair is powered by a single motor for pivotal displacement relative to the seat, with a component of force created by such pivoting oppositely though essentially rectilinearly shifting the entire chair relative to the base. In the previous embodiment, chair 10, the seat was rectilinearly powered, as opposed to pivotally powering the back as is done with chair 300.

structurally, the two-way fluid motor 302, comprising a cylinder 304 and a piston rod 306, is interposed between the frame 32 and seat 26 and the back 16, the piston rod 306 being pivotally joined by pin 308 to the depending integral link 142. The cylinder 304 is integrally joined, through lug 310, pin 312 and anchor bracket 314, to a pair of diagonal frame members 316 and 318. The frame members 316 and 318 are integrally joined, as for example by welding, to the frame 32. Thus, under control of the dentist, actuation of the motor 302 to advance and retract the piston rod 306 will in turn rotate the link 142 along with the back 16 clockwise and counterclockwise, respectively, around pin 48, as viewed in FIGURE 4, thereby controlling the pivotal disposition of the back 16 relative to the seat 26.

A linkage system, generally designated 320 is interposed between the back 16 and the seat 26 and is anchored to the base 60 so that the seat 26 will be automatically rectilinear through oppositely displaced as the back 16 is reclined or erected, in whole or in part, responsive to actuation of the motor 302. Structurally, a swivel connection 322 pivotally joins a lug 323, which lug integrally depends from the frame 18, to the linkage system 320 at recessed block. The block 324 is integrally attached to the left end of the link 330, as viewed in FIGURES 4 and 5.

The link 330 is rotatably joined at pin connection 332 to a diagonal link 334. The diagonal link 334 is joined at pin 336 for pivotal movement relative to the seat frame 32, the pin 336 being retained in an anchor bracket or lug 338 integrally fastened to the seat frame 32. The opposite end of the diagonal link 334 is pivotally joined at pin connection 340 to a link 342 which extends generally parallel but offset from the link 330. A pin connection 344 joins the back end of the link 34-2 to an anchor bracket 346 which is suitably integrally secured to the base 60 of the chair.

The operation of chair 300 is essentially identical to the operation of the chair 10 previously described, except that actuation of the fluid motor 302 alters the pivotal position of the back 16 relative to the seat 26 and such actuation, through the linkage system 320, causes the seat 26 to be essentially rectilinearly displaced across the base 16 in a direction opposite to the pivotal change of the back 16. Thus, using the chair 10, actuation of the motor 120 rectilinearly displaces the seat 26 across the base thereby causing the back 16 to pivot an amount proportional to such rectilinear displacement; and, using the chair 300, actuation of the motor 302 pivotally repositions the back 16 relative to the seat and thereby causes the seat 26 to be rectilinearly displaced across the base responsive to such displacement.

It is to be appreciated that the link 330 of the linkage system 320 could comprise telescopic members to accommodate rapid manual erection of the back 16 when the patient is choking or the like. Using such telescope members, it would be necessary that the base plate 72 be inclined somewhat with respect to the horizontal so that when under compression the telescopic members comprising link 330 will be displaced unitarily counter to gravity as the back 16 is reclined and when under tension one such telescopic member will move responsive to the force of gravity generally in unison with the forced displacement of the other telescopic members induced by erection of the back 16.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive. The scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore to be embraced therein.

What is therefore claimed and desired to be secured by US. Letters Patent is:

1. In a base-mounted, reclining dental chair and the like adapted to maintain a patients head Within a convenient working area between narrowly spaced vertically extending limits without regard to the relative orientation of the components of the chair comprising a back portion pivotally associated with and supported in cantilever relation at the rear of a seat portion of the chair, antifriction means interposed between the seat and the base accommodating ready selective displacement of the chair across the base, a selectively operable single power mechanism interposed between a fixed anchor and the chair and linkage interposed between the back and seat of the chair and the base accommodating reorientation of the patient and the chair by concurrent displacement of the chair across the base and pivoting in exact time relation of the chair back relative to the chair seat intermediate an erect nearly vertical position and a fully reclined substantially horizontal position, and other selectively operable power means solely for changing the elevation of the chair.

2. In a method of manipulating a base-supported dental or like chair having a back movable from a substantially vertically erect position to a substantially horizontally reclined position comprising the steps of: (a) lowering the headrest portion of the back of the chair essentially vertically downward within a narrow vertical corridor intermediate the erect and reclined positions by synchronously (l) arcuately pivoting the back downwardly relative to the seat about a pivotal axis disposed in the region between the back and the seat with the back being cantilever-supported only in the mentioned region and (2) jointly advancing the back and the seat across the base so that the effective horizontal rearward movement of the headrest portion is substantially equal to the effective horizontal forward movement of the seat at any instant of time during the pivoting and advancing, (b) elevating the headrest portion of the back of the chair essentially vertically upward within the narrow vertical corridor intermediate the erect and reclined positions by synchronously (l) arcuately pivoting the back upwardly relative to the seat about the pivotal axis and (2) jointly rearwardly displacing the back and the seat across the base so that the effective horizontal forward movement of the headrest caused by the pivoting is substantially equal to the effective horizontal rearward displacement of the seat at any instant in time during the pivoting and displacing.

3. In a reclining chair for retaining an occupants head at any selected one of several available elevations within close horizontally spaced limits no matter how the chair is inclined relative to the vertical, the chair comprising a back portion and a seat portion, the back portion being mechanically movable through pivot action between a primarily vertical disposition and a primarily horizontal disposition, a base interposed between the floor and the seat of the chair, antifriction means supporting the chair for essentially rectilinear displacement to and fro across the base, selectively-controlled motor means disposed to directly displace one said chair portion in the manner mentioned between available positions, and pivotally-related linkage means disposed generally beneath the seat and interposed between said chair portions, said linkage restraining the other chair portion in a selected position when the motor means are inactive, said displacement of the one chair portion causing the linkage at least in part to follow said one portion when the motor means are active with the linkage follow action accommodating the mentioned displacement of the other chair portion to retain the occnpants head within the close horizontally spaced limits at all times.

4. An apparatus as defined in claim 3 wherein said linkage means comprises telescopic members adapted to be telescopically extended by manually elevating the back relative to the seat while retaining the seat in an essentially stationary position so that the occupant may be promptly moved from a reclined position to an erect seated position, when desired.

References Cited UNITED STATES PATENTS 1,822,427 9/1931 Wenn et a1. 297342 1 0 2,028,633 1/1936 Thomas 297-622 3,172,699 3/ 1965 Naughton 297330 3,222,105 12/1965 Cross 297-314 3,224,808 12/ 1965 Spielman 297-378 3,232,575 2/1966 Ferro 297--329 3,329,463 7/1967 Zimmerman 297 342 FOREIGN PATENTS 15,112 9/ 1897 Switzerland.

US. Cl. X.R.

Images