US2987116A

US2987116A - Contour chair

Info

Publication number: US2987116A
Application number: US730008A
Authority: US
Inventors: Sanford S Golden
Original assignee: Ritter Co Inc
Current assignee: Ritter Co Inc
Priority date: 1956-06-20
Filing date: 1958-04-21
Publication date: 1961-06-06
Anticipated expiration: 1978-06-06

Description

June 6, 1961 s. s. GOLDEN 2,987,116

CONTOUR CHAIR Original Filed June 20, 1956 4 Sheets-Sheet l /NVNTOI?. SAM-0R0 5. GOLDATN BY H/$ HTT KNLY MCZM 4 S. S. GOLDEN June 6, 1961 CONTOUR CHAIR 4 Sheets-Sheet 2 Origmal Filed June 20, 1956 INVEZNTOK". SANFORD 5. GOLDEN BY HIS HTTOENEYd.

June 6, 1961 s. s. GOLDEN 2,987,116

CONTOUR CHAIR Origmal Filed June 20, 1956 4 Sheets-Sheet 3 INVENTOR. SANFORD 5. 601.0!

BY HIS HTTORNE.

June 6, 1961 s. s. GOLDEN 2,987,116

CONTOUR CHAIR Origlnal Filed June 20, 1956 4 Sheets-Sheet 4 ZZZ 205 I70 204 2/2 INVENTOR. SHNFORD 5. GOLDEN BY H/5 ATTORNEYS 2,987,116 CONTOUR CHAIR Sanford S. Golden, Los Angeles, Calif., assignor to Ritter Company, Inc., Rochester, N.Y., a corporation of Delaware Original application June 20, 1956, Ser. No. 592,652.

gigiggg and this application Apr. 21, 1958, Ser. No.

16 Claims. ((115-191) This application is a division of my copending application Ser. No. 592,652 filed June 20, 1956.

The present invention relates in general to chairs or seats and, more particularly, to contour chairs or seats, a primary object of the invention being to provide a contour seat having a longitudinal configuration which provides optimum comfort and minimizes bodily fatigue even when the user assumes one position for long periods of time. The principles of my invention may be incorporated in contoured seats or supports for reclining for many purposes as, for example, dental chairs, airplane and railroad seats, contoured bathtubs, steamship chairs and recuperating chairs for hospitals.

An important object of the invention is to provide a contour s at having a longitudinal configuration which results in conditions of maximum comfort and minimum fatigue by properly relating the seat configuration to anatomical characteristics and dimensions. More specifically, an important object of the invention is to provide an orthopedically correct seat configuration, which results in a load distribution over the supporting surface proportional to the distribution of body mass thereover so that non-uniform load concentrations at various points on the supporting surface are avoided, thereby providing maximum comfort and minimum fatigue even though a single bodily position is maintained for prolonged intervals.

Another object of the invention is to provide a longitudinal seat configuration which is the result of accurate anatomical analysis to provide an accurate relation between load distribution and the distribution of body mass over the supporting surface.

The foregoing general objects and advantages of the present invention are attained by providing a contour seat having an intermediate, substantially circularly arcuate, concave section adapted to support the hips and the adjacent portions of the back and legs, a first substantially linear, terminal section tangent or approximately tangent at one end to one end of the concave section and adapted to support the back and shoulders, an intermediate, substantially circularly arcuate, convex section tangent or approximately tangent at one end to the other end of the concave section and adapted to support the legs in the vicinities of the knees, and a second substantially linear, terminal section tangent or approximately tangent at one end to the other end of the convex section and adapted to support the lower extremities of the legs. Another important object of the invention is to provide a contour seat having the foregoing concave, convex and linear sections.

Another object of the invention is to provide a contour seat having a concave intermediate section defined by the equation In the foregoing equation, the x and y values are taken along x and y axes which intersect at an origin on the concave intermediate section between the ends thereof for one position of the contour seat relative to such axes, the x axis extending generally longitudinally of the contour seat in the horizontal direction and the y axis extending generally transversely thereof in the vertical direction.

Patented June 6, 1961 'ice Another object of the invention is to provide a contour seat wherein the first linear section mentioned, i.e., the back and shoulder supporting section, is within an angular range of 10 on either side of a line the location of which, relative to the x and y axes mentioned and for the same position of the contour seat relative thereto, is represented by the equation The foregoing equations for the concave and first linear sections of the contour seat are applicable to seats for different purposes with slightly different x intervals for the concave sections thereof, examples being a contour seat intended primarily for use in a dental chair and a contour seat for transportation purposes.

Another object of the invention is to provide a dental chair having a convex surface for supporting the knee region the equation for which, relative to the x and y axes and for the position of the contour seat relative I0 such axes mentioned above, is

the comparable equation of a transportation seat of the invention, with slightly different x intervals, as will be discussed hereinafter, being Another object is to provide a contour seat for a dental chair having a second linear section for supporting the lower extremities of the legs which is within an angular range of 10 on either side of a line whose a tion, relative to the x and y axes and for the contour seat position mentioned above, is represented by th equation y=0.0875x+1l.041

the analogous equation for the transportation contour seat of the invention, with slightly different x intervals;

being Contour seats for dental and transportation chairs having longitudinal configurations in accordance withthe equations given above achieve maximum bodily comfort and minimum fatigue, even though one bodily position is assumed for long periods, by distributing the load in proportion to the body mass throughout the various contour seat sections, which is an important feature of the invention.

Another object of the invention is to provide a chairwhich includes a base and which includes means mounting the coutour seat on the base for pivotal fore and aft movement of the seat relative to the base about a horizontal pivot axis through the origin at the intersection of the x and y axes mentioned above, i.e., about a horizontal pivot. axis intersecting the concave intermediate section of the contour seat at a point thereon between the ends thereof, and slightly rearwardly of a point midway between the ends thereof. With this construction, the contour seat is tilted forwardly or rearwardly about a horizontal pivot axis extending substantially through the mid-sacral area for optimum comfort, which is an important feature.

Another object of the invention is to provide a chair which includes a foot rest adjacent the lower or forward extremity of the second or leg-supporting linear section of the contour seat and which is mounted on such section of the contour seat for movement along a linear'path which constitutes an extension of such seat section. Thus, the foot rest may be moved inwardly or outwardly, i.e., rearwardly or forwardly, to in effect shorten or lengthen the leg-supporting linear section of the contour seat to accommodate different leg lengths without changing the contour or configuration hereinbefore outlined. Another object is to provide means for latching the foot rest in different fore and aft positions.

Another object of the invention is to provide a head rest adjacent the upper or rearward end of the first or back-supporting linear section of the contour seat.

Another object is to provide a head rest which-is contoured transversely of the seat in an anatomically correct manner so as to provide maximum comfort. More particularly, an object in this connection is to provide a head rest which, considered transversely of the contour seat, includes an intermediate concave section fianked by two lateral sections, the equation for the concave section to achieve maximum comfort and minimum fatigue, taken relative to x and y axes intersecting at an Origin at the center of curvature of the concave section, being the equation for one of the lateral sections of the head rest, relative to the same axes being and the equation for the other lateral section of the head rest, again for the same axes being A further object of the invention is to provide a head rest which is pivotally mounted on a head-rest support for pivotal fore and aft movement, means being provided to lock the head rest relative to the head-rest support in any one of a plurality of angular positions.

Another object is to provide means mounting the headrest support for up and down reciprocatory movement relative to the contour seat, means mounting the head-rest support for fore and aft pivotal movement relative to the seat, locking means for locking the head-rest support against up and down reciprocatory movement in any one of a plurality of positions, another locking means for locking the head-rest support relative to the seat against fore and aft pivotal movement in any one of a plurality of angular positions, and common control means for locking and unlocking both of these locking means. A related object is to provide a common control means which includes a common control element, means connecting such common control element to the locking means first mentioned for locking and unlocking such locking means in response to in and out reciprocatory movement of the common control element, and means connecting the common control element to the other locking means mentioned for locking and unlocking such other locking means in response to rotational movement of the common control element. Thus, either of the locking means for the head-rest support relative to the seat may be locked or unlocked by means of the same common control element merely by varying the type of motion imparted to such control element.

An important object of the invention is to provide a dental chair which enables the dentist to remain seated at all times while working on a patient. A related object is to provide a dental chair having inclination and elevation controls operable by the dentists knees and feet from a seated position.

More particularly, an important object of the invention is to provide a dental chair having a base for the seat thereof which is generally U-shaped and which includes two horizontally-spaced arm-rest supports between which the contour seat is located, one of the armrest supports having thereon knee-operable control elements for energizing bidirectionally-energizable seat tilting means carried by the base in one direction or the other so as to tilt the seat forwardly or rearwardly. With this construction, the dentist may thus control the inclination of the contour seat in the fore and aft direction with his knees without rising from a seated position, which is an important feature.

It will be seen from the foregoing discussion that not only does the present invention provide a contour seat resulting in optimum comfort and minimum fatigue from the standpoint of the user, but it also provides, in a dental chair, an installation with numerous advantages from the standpoint of the dentist, as well as from the standpoint of the patient, which is an important feature.

The foregoing objects, advantages, features and results of the present invention, together with various other objects, advantages, features and results thereof which will become apparent, may be attained with the exemplary embodiments of the invention which are illustrated in the accompanying drawings and which are described in detail hereinafter. Referring to the drawings:

FIG. 1 is a diagrammatic view illustrating the longitudinal configuration or contour of a dental seat of the invention;

FIG. 2 is a diagrammatic view illustrating a transportation seat contour of the invention;

FIG. 3 is a diagrammatic view duplicating FIG. 1, but illustrating contour ranges for two terminal sections of the contour seat of FIG. 1;

FIG. 4 is a diagrammatic view illustrating the outline of a head rest of the invention;

FIG. 5 is a diagrammatic view illustrating the transverse configuration or contour of this head rest;

FIG. 6 is a perspective view of a dental chair embodying the invention;

FIG. 7 is an enlarged, fragmentary perspective view illustrating a seat tilting means embodied in the dental chair of FIG. 6;

FIG. 8 is an enlarged, fragmentary perspective view of a seat elevating means embodied in the dental chair of the invention;

FIG. 9 is an enlarged, fragmentary perspective view of an adjustable foot rest embodied in the dental chair:

FIG. 10 is an enlarged, fragmentary perspective view of a head-rest supporting and adjusting structure embodied in the dental chair;

FIG. 11 is a vertical sectional view through the upper end of FIG. 10 and illustrating means for adjusting the head rest relative to a head-rest support in a fore and aft direction;

FIG. 12 is a fragmentary vertical sectional view through the lower end of FIG. 10 and illustrating means for adjusting the head-rest support relative to the seat in a generally vertical direction and in a fore and aft direction;

FIG. 13 is a fragmentary sectional view taken along the arrowed line 13-13 of FIG. 12; and

FIG. 14 is a fragmentary sectional view taken along the arrowed line 1414 of FIG. 12 of the drawings.

Referring to FIG. 1 of the drawings, illustrated therein is the longitudinal contour or configuration of a contour seat 20 for a dental chair 22, FIG. 6, the entire seat 20 being pivotable in the fore and aft direction about a transverse, horizontal pivot axis extending approximately through a point 24, as will be discussed in more detail hereinafter. The contour seat 20 may be regarded as divided longitudinally into an intermediate concave section 26 for supporting the hips and portions of the back and legs thereadjacent, a first substantially linear, terminal section 28 for supporting the upper portions of the back and the shoulders and approximately tangent to the concave section 26 at a point 30, an intermediate, convex section 32 for supporting the legs in the regions of the knees and approximately tangent to the concave section 26 at a point 34, and a second substantially linear, terminal section '36 for supporting the lower extremities of the legs and approximately tangent to the convex section 32 at a point 38. As will be discussed in more detail hereinafter, a head rest 40 and a foot rest 42 are mounted on the contour seat 29 adjacent the upper or rearward end of thelinear section-28 and adjacent the lower or forward end of the linear section 36, respectively, so as to support the head and the feet, respectively.

In order to attain the load distribution proportional to body mass hereinbefore discussed so as to provide maximum comfort with minimum fatigue, it is essential that the

sections

26, 28, 32 and 36 of the seat 20 be provided with approximately specific contours and approximately specific interrelationships between the contours thereof, this being particularly true of the concave section 26 and the convex section 32. These contours and contour relations can best be presented by expressing the configurations of the various sections of the seat 20 relative to the common set of x and y axes of FIG. 1 of the drawings, these axes having their approximate origin at the hereinbefore-discussed pivot point 24 for the contour seat. The equations hereinafter given are relative to these x and y axes and are for one position of the contour seat 20 relative to the pivot point or origin 24.

The equation for the concave section 26 is the foregoing equation applying throughout an x interval of 10.29 to +9.19. The foregoing values for x are in units, the numerical value of the unit being selected in accordance with the overall chair length desired.

The equation for the linear section 28 of the contour seat 20 is throughout an x interval of +9.19 to +50.00.

The equation for the convex section 32 of the contour seat 20, throughout an x interval of l9.96 to 10.29, is

the equation for the linear section 36 of the contour seat being y=0.0875x+l1.041

throughout an x interval of 50.00 to -l9.96.

With the over-all longitudinal contour provided by the foregoing equations, the desired conditions of maximum comfort and minimum bodily fatigue are achieved in a dental seat, which is an important feature of the invention. In FIG. 1, and also in FIGS. 2 and 3, the line derived in accordance with the above, represents the approximate load line with a person seated or reclining in the chair. The load line will be below the surface by an amount which depends upon the thickness of the upholstery used.

Considering now the contour seat, designated by the numeral 50, illustrated in FIG. 2 of the drawing, this seat is intended primarily for transportation purposes and, while the general contour is very similar to that of the dental seat 20, there are minor diflerences which will. be considered hereinafter. Generally speaking, the contour seat 50 is pivotable in the fore and aft direction about a transverse, horizontal axis approximately through a point 54 which also approximates the origin of the x and y axes of FIG. 2. The contour seat 50 includm a concave section 56 corresponding to the concave section 26 and passing approximately through the pivot point or origin 54, a first linear section 58 corresponding to the linear section 28 and approximately tangent to the concave section 56 at a point 60, a concave section 62 corresponding to the convex section 32 and approximately tangent to the concave section 56 at a point 64, and a second linear section '66 corresponding to the linear section 36 and approximately tangent to the convex section 62 at a point 68.

The equations for the concave and

linear sections

56 and 58 are preferably identical to the hereinbefore-presented equations for the concave and

linear sections

26 and 28, respectively, the x interval for the linear section 58' also being preferably identical to the x interval previously given for the linear section 28. The x interval for the concave section 56 is slightly greater than that of the concave section 26, ranging from l0.74 to +9.19. The effect of this difference in the x interval is to make the concave section 56 of the contour seat 50 somewhat deeper than the concave section 26 of the contour seat 20 for greater traveling comfort.

The equation for the convex section 62 of the contour seat 50, throughout an x interval of 19.87 to l0.74, is

and the equation for the linear section 66, throughout an x interval of 50.00 to -19.87, is

As hereinbefore stated, the foregoing contours of and contour relationships between the concave and

convex sections

26 and 32 and the concave and

convex sections

56 and 62 are particularly important. However, the slopes of the

linear sections

28 and 36 and the slopes of the

linear sections

58 and 66 may be varied somewhat, simultaneously varying the locations of the points of tangency to the concave and convex sections and the x intervals of the concave and convex sections correspondingly. The permissible ranges of slope variations for the

linear sections

28 and 36 of the contour seat 20 are illustrated in FIG. 3 of the drawings, the same ranges applying to the contour seat 50 as well. It will be noted that the linear section 28 may be shifted angularly up to approximately l0 on either side of the solid line 28, the location of which corresponds to the equation previously given. The extreme positions for the linear section 28 are represented by the dotted

lines

28a and 28b, the corresponding points of tangency to the concave section 26 being indicated by the points 30a and 3012, respectively. Similarly, the slope of the linear section 36 relative to the convex section 32 may be varied throughout a range of approximately 10-" on either side of the solid line position shown for the linear section 36, which position corresponds to the equation previously given. The extreme locations for the linear section 36 are illustrated by the dotted lines 36a and 36b, the corresponding points of tangency to the convex section 32 being indicated by the points 38a and 38b, respectively. It will be seen that, even though the slopes of the

linear sections

28 and 36 are variable in this manner, such variations in the slopes thereof do not alter the equations of the concave and

convex sections

26 and 32, nor do they alter the relation between the contours of these sections. However, varying theslopes of the

linear sections

28 and 36 does vary the x intervals of the concave and

convex sections

26 and 32.

Within the ranges of angular deviation for the

linear sections

28 and 36 shown in FIG. 3 of the drawings, with respect to thepreferred positions of the

linear sections

28 and 36 relative to the concave and

convex sections

26 and 32 given by the equations hereinbefore presented, the desired proportionality relationship between load distribution and .body mass is achieved to provide maximum comfort withminimum bodily fatigue.

Turning now FIGS. 4 and 5 of the drawings, the head rest 40 is contoured transversely thereof, i.e., transversely of the contour seat with which it is used. As shown in FIG. 5, the head rest 40, considered transversely, includes a concave intermediate section 70 flanked by two

lateral sections

72 and 74 respectively tangent to the concave section 70 at the

points

76 and 78. Considering the transverse contours of the concave section 70 and the

lateral sections

72 and 74 relative to the x and y axes shown, which have their origin 80 at the center of curvature of the concave section 70, the equation for the concave section 70, within an x interval of l.8l2 to +1.812, is

the equation for the linear section 72 is throughout an x interval of from l0.00 to 1.812, and

the equation for the linear section 74, throughout an x interval of from +1.8l2 to +1000, is

Turning now to FIGS. 6 to 14 of the drawings, the dental chair 22 illustrated therein incorporates the contour seat 20 carrying the head rest 40 and the foot rest 42, which will be described in detail hereinafter. The contour seat 20 is pivotally mounted for fore and aft movement on a base 86 which, in turn, is mounted on a sub-base 88 for pivotal movement about a vertical axis so that the dental chair 22 may be rotated about such axis in the usual manner.

As best shown in FIG. 6 of the drawings, the base 86 is generally U-shaped and includes transversely spaced supports 90 for arm rests 92, the concave section 26 of the contour seat 20 being disposed between the arm rest supports. The contour seat 20 is mounted for pivotal fore and aft movement about a horizontal, transverse pivot axis extending approximately through a point on the concave section 26 corresponding to the hereinbefore-discussed origin 24. Referring to FIG. 7 of the drawings, the concave section 26 of the contour seat 20 carries axially aligned stub shafts 94, only one of which is visible, these stub shafts being journaled in bearings 96 carried by the base 86. The horizontal pivot axis provided by the stub shafts 94 extends through the concave section 26 of the contour seat 20 intermediate the ends thereof and, more accurately, extends through the hereinbeforediscussed origin 24, as mentioned above.

The dental chair 22 is provided with bidirectionallyenergizable seat tilting means 98 for varying the inclination of the seat in the fore and aft direction throughout an angle of the order of magnitude of 35. The seat tilting means 98 includes a reversible electric motor 100 mounted on the base 86 and having on its shaft a gear 1.02 meshed with a gear 104- fixed on one of the stub shafts 94. Thus, energization of the motor 100 in one direction tilts the contour seat 20 forwardly, while energization of the motor in the opposite direction tilts the seat rearwardly.

An important feature of the invention is that the direction of energization of the seat tilting means 98 is determined by knee-operable control switches 106 mounted on one of the arm-rest supports 96 beneath the arm rest 92 thereon in positions readily accessible to the dentists knees when he is seated alongside the dental chair 22, the control switches 106 being connected to the motor 100 as shown in FIG. 7 of the drawings. Thus, by pressing one of the control switches 106 with one knee, the dentist may tilt the contour seat 20 rearwardly, and by pressing the other control switch 106 with his other knee, he may tilt the seat forwardly, all While remaining in a seated position alongside the dental chair 22 and without interrupting his work on the patient. 1

Referring to FIG. 8 of the drawings, the numeral 118 designates a tubular rack having at its upper end a flanged cap 112 on which the base 86 is mounted, the tubular rack 110 being vertically movable on a guidepost 114 having a foot 116 suitably secured to the sub-base'88 and being further guided by bearings 118 encircling the tubular rack and connected to the sub-base. With this construction, the dental chair 22 may be rotated relative to the sub-base 88 about a vertical axis through any 'desired angle, such as 75 or more, and may also be moved upwardly and downwardly relative to the sub-base. For the latter purpose, the dental chair 22 is provided with a bidirectionally-cnergizable seat elevating means 120 shown as including a reversible electric motor 122 having on its shaft 2. gear 124 meshing with a gear 126 on an input shaft 128 of a speed reducing unit 130. The latter is provided with an output shaft 132 having thereon a gear I 134 meshing with the tubular rack to move the base 86 and the contour seat 20 carried thereby upwardly and downwardly, depending upon the direction of rotation of the motor 122. To eliminate back lash in the gearing system, an idler gear 136 suitably mounted on the subbase 88 is also meshed with the tubular rack 110, on the opposite side thereof from the gear 134.

An important feature of the invention is that the reversible motor 122 is actuated by foot-operable control switches, or pedal switches, 138 set in an forming parts of a marginal flange 140 on the sub-base, this flange being adapted to seat on the floor on which the sub-base is mounted. Thus, the dentist may readily depress one or the other of the pedal switches 138 to raise or lower the dental chair 22 without changing his working position and, at the same time, the switches are out of the way.

Another important feature is that, when the dental chair 22 is in the normal working position about its vertical axis of rotation, as shown in FIG. 6 of the drawings, the pedal switches 138 are in substantially the same vertical planes as the knee switches 106. Thus, when the dental chair is in this normal working position, the dentist can operate either the knee switches 106 to tilt the contour seat 26' forwardly or rearwardly, or the pedal switches 138 to raise or lower the seat, all without rising from a seated working position alongside the chair. Thus, in addition to the hereinbefore discussed advantages to the patient, the dental chair of the invention presents numerous advantages to the dentist also.

Referring now to FIG. 9 of the drawings, the foot rest 42 includes a foot-rest frame 142 having connected thereto a transverse frame member 144 to which fore-and-aftextending bars or rods 146 are connected, these bars being interconnected at their rearward ends by a transverse frame member 148 to provide a rigid supporting structure for the foot-rest frame 142. The bars 146 and the transverse frame member 148 are disposed within the lower or forward end of the linear section 36 of the contour seat 20 with the bars 146 extending parallel to this linear section. The bars 146 are movable along rollers 156 within and suitably mounted on the linear section 36 of the contour seat 29 so that the foot rest 42 is movable inwardly and outwardly along a path which forms an extension of the linear section 36. Thus, the effective length of the linear section 36 of the contour seat 20 may be varied to accommodate varying leg lengths with out altering the contours and contour relations of the seat 20 which were discussed previously herein, which is an important feature.

In order to lock the foot rest 42 in any one of a plurality of fore and aft positions, a latch member 152 is mounted on an arm 154 pivotally connected to a bracket 156 at 158, this bracket being connected to the frame member 148. At the outer end of the arm, which proiects through a longitudinal slot 160 in one side of the linear section 36 of the contour seat 20, is a handle 162 which may be either hand or foot operated. The bracket 156 includes an arm 164 which serves as a seat for a compression spring 166, the spring also being seated against the latch member 152 to bias the latter into engagement with a rack 168 within the linear section 36 of the contour seat. As will be apparent, by depressing the latch member 152 against the action of the spring 166, the foot rest 42 may be moved forwardly or rearwardly as required to accommodate it to a particular individual, and may then be latched in the desired position merely by releasing the handle 162.

Referring to FIGS. 6 and 10 of the drawings, the head rest 49 is mounted on a head-rest support 170' for fore and aft pivotal movement about a transverse horizontal axis in a manner to be described hereinafter, the head rest being notched, as indicated at 172 in FIG. 6, to permit such fore and aft pivotal movement of the head rest relative to the support. The head-rest support 170 extends downwardly into the upper or rearward linear section 28 of the contour seat 20 and is mounted on the internal structure of the contour seat for upward and downward reciprocatory movement and for fore and aft pivotal movement about a transverse horizontal axis, all as will be described in detail later herein, the upper end of the linear section 28 of the seat being notched, as indicated at 174, to permit such fore and aft pivotal movement of the head-rest support.

To permit changing head rests 40, the head-rest support 170 is made in readily separable, upper and

lower sections

176 and 178, the upper section, as shown in FIGS. and 11, being provided with a transverse shaft 180 at its upper end within the head rest. Also within the head rest is a clamp 182 which is connected to the internal structure of the head rest to support same and which encircles the shaft 180. This clamp includes two arms through which a screw 184 extends, this screw being threaded into one of the arms of the clamp and being seated against the other arm thereof, as best shown in FIG. 11. A handle 186 is set in a recess 188 in the back of the head rest 40 and is provided with a tubular stem 190 which is telescoped over the outer end of the screw 184 and which is biased inwardly by a compression spring 192, there being a pin 194 and slot 196 connection between the tubular stem 190 and the screw 184 which permits pulling the handle 186 outwardly out of this recess 188 for accessibility, or it may be rotated Within the recess if desired. As will be apparent, by rotating the handle 186 to rotate the screw 184, the clamp 182 may be caused to engage or disengage the shaft 180 to lock the head rest 40 in a predetermined angular, fore and aft position about the shaft, or to release it for movement to another position. As best shown in FIG. 10, a stop pin 198 on the clamp 182 is engageable with either of two stop pins 200 on the shaft 180 to limit fore and aft pivotal movement of the head rest relative to the support 170, the angular range of such movement preferably being of the order of magnitude of 30.

Referring to FIGS. 10 and 12 to 14 of the drawings, the lower section 178 of the head-rest support 170 is provided With a transverse tubular shaft 204 which extends into a clamp 206 similar to the clamp 182, the clamp 206 being connected to a sleeve 208 which is vertically slidable, i.e., slidable longitudinally of the linear section 28 of the seat 20, on a guide rod or tube 210 hav ing secured to its ends brackets 212 for attachment to the internal structure of the linear section 28 of the seat in a manner not specifically shown. To prevent rotation of the sleeve 208 about the axis of the guide tube 210, the latter is provided with a slot 214 receiving pins 216 on the sleeve. The shaft 204 is retained within the clamp 206 by means of a shaft 218, FIG. 14, extending through the shaft 204 and the lower section 178 of support 170, the shaft 218 having a snap ring 220 on its outer end.

Extending through arms of the clamp 206 and threaded into one of such arms is a screw 222 by means of which the clamp may be engaged with and disengaged from the tubular shaft 204 to permit fore and aft tilting of the head-rest support 170 so as to move the head rest 40 forwardly and rearwardly. A stop pin 224, FIG. 12, on the tubular shaft 204 engageable with stop pins 226 on the clamp 206 limits the angular fore and aft movement of the head-rest support 170. Preferably, the range of fore and aft pivotal movement of the headrest support 170 is of the order of magnitude of 30, 20 forwardly of alignment with the linear section 28 of the contour seat 20 and 10 rearwardly of such alignment.

The screw 222 has a pin 228 and slot 230 connection to a handle stem 232 telescoped over the outer or rearward end of the screw, as shown in FIGS. 12 and 13. The handle stem 232 extends outwardly through a vertical or longitudinal slot 234 in the rear wall of the linear shaft 204 to permit fore and aft pivotal adjustment of the head-rest support 170. Conversely, by rotating the handle 236 in the opposite direction, the clamp 206 is engaged with the shaft 204 to lock the head-rest support in any desired position.

Interconnecting the brackets 212 is an apertured latch strip 240 adapted to receive a pin 242 on a latch element 244 and provided therein with a guide slot 246 for a guide element 248 on the latch element 244, the element 248 in the slot 246 guiding the latch element 244 longitudinally of the linear section 28 of the contour seat 20 in response to movement of the clamp 206, the sleeve 208, and associated elements, longitudinally of such linear section along the guide tube 210.

The handle stem 232 extends through the latch element 244, as shown in FIGS. 10, 12 and 13. The latch element 244 is seated against a shoulder, provided by a snap ring 250, on the handle stem and is biased against such shoulder by a compression spring 252. As will be apparent, by pulling outwardly on the handle 236 to the limit of the pin-slot connection 228-230, the latch pin 242 may be withdrawn from one of the apertures in the latch strip 240 to permit upward or downward movement of the head-rest support 170, the clamp 206, the sleeve 208, and associated elements, so as to provide for adjustment of the vertical position of the head rest 40, i.e., adjustment of the position of the head rest longitudinally of the linear section 28 of the contour seat 20. Upon completion of the desired longitudinal adjustment of the head rest 40, the handle 236 may be released to permit the latch pin 242 to enter another aperture in the latch strip 240.

It will be noted that the handle 236 serves as a common control element for both the locking means for locking the head-rest support 170 against reciprocatory up and down movement, i.e., reciprocatory movement in the direction of the linear section 28 of the contour seat 20 and the locking means for locking the head-rest support against fore and aft pivotal movement. In other words, by rotating the handle 236, the locking means controlling fore and aft pivotal movement of the head-rest support 170 is operated, and by moving the handle inwardly or outwardly, the locking means for controlling reciprocatory up and down movement of the head-rest support is operated. Thus, a single handle controls both locking means, which is an important feature.

Although various exemplary embodiments of the present invention have been disclosed herein for purposes of illustration, it will be understood that various changes, modifications and substitutions may be incorporated in such embodiments without departing from the spirit of the invention as defined by the claims hereinafter appearing.

I claim as my invention: I

1. A contour chair including a contour support having an intermediate, substantially circularly arcuate, concave buttocks section; a first substantially linear, terminal back section tangent at one end to one end of said concave buttocks section; an intermediate, substantially circulanly 'arcuate, convex knee section tangent at one end to the other end of said concave buttocks section; and a second substantially linear, terminal leg section tangent at one end to the other end of said convex knee section, wherein a projection of said leg section toward said back section has an intersecting relationship with said back section.

2. A contour chair including a contour seat having an intermediate, concave section, a first linear, terminal section approximately tangent at one end to one end of said concave section, an intermediate, convex section approximately tangent at one end to the other end of said concave section, and a second linear, terminal section approximately tangent at one end to the other end of said convex section, the equation for said concave section, relative to x and y axes intersecting at an origin 11 on said concave section intermediate said ends thereof, being, for one position of said contour seat relative to said axes,

and said first linear section being within an angular range of on either side of a line the location of which, relative to said axes and for said one position of said contour seat, is represented by the equation 3. A contour chair including: a contour seat having in intermediate, concave section, a first linear, terminal section approximately tangent at one end to one end of said concave section, an intermediate, convex section approximately tangent at one end to the other end of said concave section, and a second linear, terminal section approximately tangent at one end to the other end of said convex section, the equation for said concave section, relative to x and y axes intersecting at an origin on said concave section intermediate said ends thereof, being, for one position of said contour seat relative to said axes,

said first linear section being within an angular range of 10 on either side of a line the location of which, relative to said axes and for said one position of said contour seat, is represented by the equation the equation for said convex section, relative to said axes and for said one position of said contour seat, being and said second linear section being within an angular range of 10 on either side of a line the location of which, relative to said axes and for said one position of said contour seat, is represented by the equation a base; and means pivotally connecting said contour seat to said base for pivotal movement relative thereto about a horizontal pivot axis extending approximately through said origin.

4. A contour chair including a contour seat having an intermediate, concave section, a first linear, terminal section approximately tangent at one end to one end of said concave section, an intermediate, convex section approximately tangent at one end to the other end of said concave section, and a second linear, terminal section approximately tangent at one end to the other'end of said convex section,'the equation for said concave section, relative to x and y axes intersecting at an origin on said concave section intermediate said ends thereof, be ing, for one position of said contour seat relative to said axes,

said first linear section being within an angular range of 10 on either side of a line the location of which, relative to said axes and for said one position of said contour seat, is represented by the equation the equation for said convex section, relative to said axes and for said one position of said contour seat, being and said second linear section being within an angular range of 10 on either side of a line the location of which, relative to said axes and for said one position of said contour seat, is represented by the equation a base; and means pivotally connecting said contour seat to'said base for pivotal movement relative thereto about a horizontal pivot axis extending approximately through said origin.

5. A contour chair according to claim 3 including in addition: an adjustable head rest adjacent the other end of said first linear section and connected to said first linear section; and an adjustable foot rest adjacent the other end of said second linear section and connected to said second linear section.

6. A contour chair according to claim 4 including in addition: an adjustable head rest adjacent the other end of said first linear section and connected to said first linear section; and an adjustable foot rest adjacent the other end of said second linear section and connected to said second linear section.

7. A contour chair including: a contour seat having an intermediate, substantially circularly arcuate, concave section, a first substantially linear, terminal section approximately tangent at one end to one end of said concave section, an intermediate, substantially circularly arcuate, convex section approximately tangent at one end to the other end of said concave section, and a second substantially linear, terminal section approximately tangent at one end to the other end of said convex section; a base for said contour seat; means mounting said contour seat on said base for fore and aft pivotal movement relative thereto about a horizontal pivot axis approximately intersecting said concave section intermediate said ends thereof; bidirectionally-energizable tilting means carried by said base for tilting said contour seat back and forth in the fore and aft direction; and knee-operable control elements carried by said base on one side thereof for energizing said seat tilting means in one direction or the other so as to tilt said contour seat forwardly or rearwardly.

8. A chair including: a seat; a base beneath said seat; means mounting said seat on said base for pivotal fore and aft movement relative to said base about a horizontal axis; bidirectionally-energizable seat tilting means carried by said base for tilting said seat forwardly or rearwardly; knee-operable control elements carried by said base on one side thereof for energizing said seat tilting means in one direction or the other so as to tilt said seat forwardly or rearwardly; a sub-base beneath said base;

means mounting said base on said sub-base for rotation of said base and said seat relative to said sub-base about a vertical axis; bidirectionally-energizable seat elevating means carried by said sub-base and connected to said base for raising and lowering said seat; and foot-operable control elements carried by said sub-base on one side thereof for energizing said'seat elevating means in one direction or the other so as to raise or lower said seat,

- vertical axis.

9. A contour chair including: a contour seat having an intermediate, substantially circularly arcuate, concave section, a first substantially linear, terminal section approximately tangent at one end to one end of said concave section,'an intermediate, substantially circular arcuate, convex section approximately tangent at one end to the other end of said concave section, and a second sub stantially linear, terminal section approximately tangent at one end to the other end of said convex section; a foot rest adjacent the other end of said second linear section; and means mounting said foot rest on said second linear section for movement along a linear path constituting an extension of said 'secondlinear section. a

10. A contour chair including a contour support having an intermediate, substantially circularly arcuate, concave buttocks section; a firstsubstantially linear, terminal back section tangent at one end to one end of said concave buttocks section; an intermediate, substantiallycircularly arcuate, convex knee section tangent, at one end to the other end of said concave buttocks section; a second substantially linear, terminal leg section tangent at one end to the other end of said convex knee section, wherein a projection of said leg section toward said back section has an intersecting relationship with said back section; a base for said contour support; and means mounting said contour support on said base for fore and aft pivotal movement relative thereto about a horizontal pivot axis substantially intersecting said concave buttocks section approximately intermediate the ends thereof.

11. A contour chair comprising contour support having a back section, a seat section and a leg rest section, each of said sections having first and second ends, the first end of said back section extending into an area to support the shoulders of the user, said seat section being of arcuately curved concave contour and the first end thereof merging smoothly with the second end of the back section, said leg rest section being of generally arcuately curved convex contour and the first end thereof merging smoothly with the second end of the seat section, the second end of the leg rest section forming a support for the calves of the legs of the user, said back, seat and leg sections forming an integral unit in which the sections are so contoured as to support the body weight of the user approximately uniformly over the extent of the body, a U-shaped yoke having legs straddling said contour support and pivot means between said contour support and said legs allowing the contour support to tilt fore and aft while the contour support maintains a body reclining on the contour support in the same relationship to the contour support.

12. A contour chair in accordance with claim 11 in which when the chair is in a normal upright position provides a seat in which the buttocks of the user is somewhat bucketed in the concave contour of the seat section and the back of the user is supported at a small rearwardly declining angle to the vertical, said chair having a horizontally extending fixed pivot located approximately on line approximately normal to the center of said seat section enabling movement of the chair to a position such that the body of the user approaches a prone position with the back lowered but with the knees raised well above the major extent of the back of the user.

13. A contour chair comprising contour support having a back section, a seat section and a leg rest section, each of said sections having first and second ends, the first end of said back section extending into an area tc support the shoulders of the user, said seat section being of arcuately curved concave contour and the first end thereof merging smoothly with the second end of the back section, said leg rest section being of generally arcuately curved convex contour and the first end thereof merging smoothly with the second end of the seat section, the second end of the leg rest section forming a support for the calves of the legs of the user, said back, seat and leg sections forming an integral unit in which the sections are so contoured as to support the body weight of the user approximately uniformly over the extent of the body, a head rest section separate from said back rest section but connected thereto and means for adjusting the level of the head rest section with respect to the level of the back rest section.

14. A contour chair comprising contour support having a back section, a seat section and a leg rest section, each of said sections having first and second ends, the first end of said back section extending into an area to support the shoulders of the user, said seat section being of arcuately curved concave contour and the first end thereof merging smoothly with the second end of the back section, said leg rest section being of generally arcuately curved convex contour and the first end thereof merging smoothly with the second end of the seat section, the second end of the leg rest section forming a support for the calves of the legs of the user, said back, seat and leg sections forming an integral unit in which the sections are so contoured as to support the body weight of the user approximately uniformly over the extent of the body, a U-shaped yoke having legs straddling said contour support, pivot means between said contour support and said legs allowing the contour support to tilt fore and aft while the contour support maintains a body reclining on the contour sup port in the same relationship to the contour support, a foot rest attached to the second end of the leg rest section and arm rests carried by said legs, said arm rests extending generally perpendicularly forward from the back rest toward the apex of the leg rest section when the back rest is in its most nearly upright position and said arm rests being above said pivot means.

15. A contour chair including a support having an intermediate, substantially circularly arcuate, concave buttocks section; a first substantially linear, terminal back section tangent at one end to one end of said concave buttocks section; an intermediate, substantially circularly arcuate, convex knee section having one of its ends connected to and aligned with the adjacent end of the said concave buttocks section; and a second substantially linear, terminal leg section tangent at one end to the other end of said convex knee section, the plane of said leg section being so disposed with respect to the plane of said back section so that said planes will intersect above said one end of said terminal back section.

16. A contour chair in accordance with claim 15 in which the support is pivoted so that when the chair is in a normal upright position it provides a seat in which the buttocks 0f the patient user is somewhat bucketed in the concave contour of the seat section and the back of the patient user is supported at a rearwardly declining angle to the vertical, said chair having a horizontally extending fixed pivot located approximately adjacent the center of said buttocks section enabling movement of the chair without shifting the patient user longitudinally of the surface of the chair to a position such that the body of the user approaches a prone position with the back lowered so that the dentist can perform work on the teeth of the patient user while the dentist is in a seated position but with the knees raised well above the major extent of the back of the user, said contour chair having a head rest section separate from the back section and having means for adjusting the level of the head rest section with respect to the level of the back rest section so that the dentist can adjust the level and longitudinally angular position of the patient users head to enable more convenient operations by the dentist.

References Cited in the file of this patent UNITED STATES PATENTS D. 176,813 Parker Jan. 31, 1956 1,814,877 Weber July 14, 1931 1,988,788 Goodman Ian. 22, 1935 2,215,540 Breuer Sept. 24, 1940 2,482,306 Waldheim Sept. 20, 1949 2,564,083 Strechert Aug. 14, 1951 2,722,967 Reinholz Nov. 8, 1955 FOREIGN PATENTS 519,067 Great Britain Mar. 15, 1940 537,707 Great Britain July 3, 1941 1,124,498 France July 2, 1956