WO2016018428A1

WO2016018428A1 - Cross-legged sitting device

Info

Publication number: WO2016018428A1
Application number: PCT/US2014/049402
Authority: WO
Inventors: Thomas C. VEATCH
Original assignee: Veatch Thomas C
Priority date: 2014-08-01
Filing date: 2014-08-01
Publication date: 2016-02-04

Abstract

A sitting device and method for yoga or 'Indian style' cross-legged sitting with greater comfort, stability, and duration and with improved core posture and reduced hunching are disclosed here. The sitting device includes a saddle shaped seat with an elevated rear edge and a lower front edge rear. The seat includes a sloped center region and downward and outward sloped side sections located on opposite sides of the center region. The heights of the rear and front edges and the shape and orientation of the center region and the side sections enable a user to sit comfortably on a flat support surface with his or her legs crossed and with his or knees and lower legs support on the support surface.

Description

CROSS-LEGGED SITTING DEVICE

TECHNICAL FIELD

The present invention relates to sitting support devices and more particularly, to support devices for cross-legged sitting.

BACKGROUND ART

Lengthy periods of restful alertness, with spine relatively erect, are enabled by postures of squatting, sitting cross-legged ("Indian style") and sitting in a chair. In yoga and meditation and for other purposes, sitting cross-legged can be a preferred posture. Have you, however, ever found sitting cross-legged to be uncomfortable, or even painful, especially over an extended time? Many do; it can be hard on your legs. A lifetime of chair use can limit hip flexibility, particularly bent-hip thigh supination flexibility (see definition below), essential to comfortable cross-legged sitting for extended times. Have you ever struggled with a slouching posture while sitting? Many do. Sitting normally makes it easy for the pelvis to tilt top-backwards, which can encourage the collapsed posture changes known as slouching and hunching.

Posterior tilt of the pelvis is typical of, and a problem with, many sitting postures, including many cross-legged sitting postures.

There is a variety of sitting support devices available for cross-legged sitting. Each of them has its own advantages and drawbacks, and none provide a shaped (as opposed to shapeless/conformable as in balls and cushions) sitting surface, provide a primary sitting surface for buttocks and upper thighs elevated between two and sixteen inches above a lower, secondary support surface whereon a side or front of a foot or a lower leg may rest, provide downward and outward sloped sitting surfaces for the upper thighs, or provide assistance to thigh supination, with a single device. Nor does a single such device also assist in top-forward tilt of the hips. Nor does a single such device also provide a backrest.

DISCLOSURE OF THE INVENTION

The present invention is a sitting device for cross-legged sitting with a primary sitting surface that provides certain structural characteristics during compression; that disposes the primary sitting surface at an elevation higher than a lower, secondary sitting surface. Both the primary and secondary sitting surfaces are gradually sloped downward and outward.

Maintaining good posture while sitting is hard without tilting hips top- forward, and sitting cross legged is hard without enough flexibility when thighs are supinated, that is, knees and feet are rotated forcibly by the body's weight crushing down on bent lower legs, and keeping hips tilted forward under these conditions, while sitting cross-legged, is even harder. The sitting device assists in thigh supination while also reducing the thigh supination flexibility required to sit cross- legged, and helps to tilt the hips top-forward, providing a foundation for balanced, erect, easeful postures that can be maintained for extended durations. Lateral support is provided by the legs.

According to an aspect of the present invention, the primary sitting surface is elevated above a support surface thereby position the user's buttocks at a high elevation than the user's knees and feet when the user's legs and feet are crossed and resting on the support surface. The problems of limited thigh supination flexibility in cross-legged sitting postures can be ameliorated in two ways, either by raising and supporting the knees, or by raising and supporting the buttocks above the feet. The former option does not reduce and can increase the top-backward hip tilting in many cross-legged sitting postures; whereas the second option enables beneficial top- forward hip tilting. Higher elevations enable cross-legged sitting with lesser degrees of thigh supination, so different users may prefer seats of different, though still anatomically reasonable, elevations.

According to a further aspect of the present invention, the primary sitting surface is substantially flat or slightly curved near the rear surface. As the primary sitting surface extends forward, it gradually slopes downward and outward so that each thigh rolls and extends outward and downward so the user's knees extend outward. The user's legs can easily ber tucked inward and the feet crossed, tice that a slope assists a body resting on the slope in rolling down the slope. A seat, therefore, that provides outward sloping thigh support areas within the primary sitting surface assists the thigh in rolling downward on that slope, or top outward.

Another important benefit of the sitting device is the angle of elevation of the longitudinal axis of the thigh relates to the angle of top-forward or top-backward tilt of the hips in an erect sitting posture, whereby if the longitudinal axis of the thigh is at an angle of elevation above the horizontal from hip to knee then top-backward tilt of the hips can follow, and if contrariwise it is below the horizontal then top-forward tilt of the hips can follow. Tall boys in school chairs may often be observed to slouch: their knees are elevated high because they have long legs, their hips are low in the short school chairs, the axis of the thigh is therefore above the horizontal from hip to knee, thence by this relationship the hips tilt top-backwards, thence the further posture changes considered collectively as slouching. According to a further aspect of the present invention, support is provided to the upper thighs of a user in a cross-legged sitting posture. The thighs in a cross-legged sitting posture are typically disposed at an outward angle.

According to the three aspects of the present invention mentioned in this paragraph, combined together, the sitting device provides support surfaces shaped and disposed so the upper thighs are supported in a position and orientation with the longitudinal axis of the thigh from hip toward knee angled downward and outward.

The sitting device includes a saddle-shaped seat with a rear edge, two curved lateral edges, and a curved front edge and a bottom surface. The seat's rear edge is elevated above the front edge when placed on a support surface. The seat also includes a sloped center region that extends downward from the rear edge to the front edge and two symmetrical side sections that curved downward and curved outward from and on opposite sides of the center region, said center region. The orientation, shape and size of the center region and the two side sections are configured to support a user sitting on said seat with his or her buttocks positioned adjacent to the rear edge and aligned over the center region and with his or her thighs extending outward and supported by the side sections. The user's knees are positioned on the support surface.

The sitting device also includes a seat base connected to said bottom surface on said seat that is configured to support the rear edge in an elevated position above the front edge thereby enabling a user to sit on said seat with his or her buttocks positioned adjacent to the rear edge and aligned over the center region and with the user's thighs extending downward and outward. Because the buttocks are elevated and partially supported, and because the thighs are partially supported and the knees extend outward and also supported by the support surface, the user can easily bend his or her knees in front of the front edge and cross his or her legs. The user can then stretch backward and straighten his or back and neck without tipping over.

More specifically, the sitting device includes a primary sitting surface having front left primary sitting surface planes and front right primary sitting surface planes each sloping downward and outward on their lines of steepest downward slope, outward at an angle between 10 and 135 degrees, measured between the vertical projection of the plane's line of steepest slope into a horizontal plane and the forward horizontal direction in that horizontal plane. The sitting surface planes are also angled downward at an angle between 3 and 70 degrees measured between the horizontal plane and the line of steepest slope.

According to an optional further aspect of the present invention, the sitting device may assist top-forward tilt of the hips with a downward, forward tilt of the upper thigh support surfaces or of the rear left and rear right primary support surfaces or of the entire primary support surface. The downward and outward angles, measured as in the previous paragraph, of the lines of steepest slope of the front right and front left primary sitting surface planes may optionally be downward between 3 and 70 degrees and outward less than 90 degrees. Optionally, also, the downward and outward angles of the lines of steepest slope of the rear right and rear left primary sitting surface planes, may be downward between 3 and 70 degrees and outward less than 90 degrees and more than 90 degrees. Optionally, also, the downward angle of the forward line projected by the midline of the seat onto the plane of the entire primary sitting surface may be downward between 3 and 70 degrees.

The sitting device may include an optional back or backrest.

According to an aspect of the present invention, the sitting device may include a curved cutout located along the front edge that enables a user to extend his or her feet or heels to rest comfortably when sitting with his or her legs crossed.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a front elevational view of a person sitting cross-legged without this sitting device.

Fig. 2 is a side elevational view of a person sitting cross-legged without this sitting device.

Fig. 3 is a front elevational view of a person sitting cross-legged with a preferred embodiment.

Fig. 4 is a side elevational view of a person sitting cross-legged with a preferred embodiment.

Fig. 5 is a right-front-top perspective view of a preferred embodiment with equal-elevation (topo) lines.

Fig. 6 is a right-front-top perspective view of a preferred embodiment with analysis indicated.

Fig. 7 is a front elevational view of a preferred embodiment.

Fig. 8 is a rear elevational view of a preferred embodiment.

Fig. 9 is a right side elevational view of a preferred embodiment.

Fig. 10 is a left side elevational view of a preferred embodiment

Fig. 1 1 is a plan view of a preferred embodiment with equal-elevation (topo) lines and cross-sectional reference lines for Figs. 12-16.

Fig. 12 is a front elevational view of a vertical section of a preferred embodiment taken along line 12-12 in Fig. 1 1.

Fig. 13 is a front elevational view of a vertical section of a preferred embodiment taken along line 13-13 in Fig. 11.

Fig. 14 is a front elevational view of a vertical section of a preferred embodiment taken along line 14-14 in Fig. 11.

Fig. 15 is a front elevational view of a vertical section of a preferred embodiment taken along line 15 - 15 in Fig. 11.

Fig. 16 is a front elevational view of a vertical section of a preferred embodiment taken along line 16-16 in Fig. 1 1.

BEST MODE FOR CARRYING OUT THE INVENTION

The invention will now be described by reference to the accompanying drawings. The illustrated embodiments and description are provided only for exemplary purposes to facilitate comprehension of the invention and should not be construed to limit the scope of the invention.

Referring to the accompanying Figs. 1-4, comparison may be made between postures of a user 100 sitting not using the sitting device shown in Figs 1 and 2, and a user 200 sitting and using the sitting device shown in Figs 3-4. It should be observed from Figs 1 and 2, that when a user is sitting with the sitting device 10, his or her knees 1 10, 112, 114, 1 16 are positioned well off the floor 118 (especially the left knee in FIG. 2, 1 12); the lumbar spine 120 has little lordosis while the hips are tucked under (top tilted back) 122; the ribcage is tilted top-forward 132, 134; the neck 140 extends forward so muscular effort must keep the head 160 facing horizontally 150. Figs 3-4 show a sitting device 10 in hidden outline with several posture differences: the knees 210, 212, 214, 216 are closer to the floor 218; the hips 222 are tilted more top-forward; the lumbar spine 220 achieves a desirable degree of lordosis otherwise more typical of a walking or standing posture; regarding the ribcage the bottom 232 is more forward and the top 234 more backward, or the thoracic spine is more balanced and erect in Fig. 4 than in Fig. 2; the head 260 is above rather than in front of the shoulders 270.

A viewer's global impression is of effort and struggle in Figs. 1-2, versus easeful stability in Figs. 3-4.

In Fig. 5 is a perspective view of the sitting device 10 showing equal- elevation, topographical lines 40. The sitting device 10 includes a curved seat top 20 supported by a base 24 comprising structural support members 30, 32 and 34 ( see Figs 6-8). The sitting device 10 includes a seat top 20 made of curved plywood approximately 3/8" thick, and the support members 30, 32, and 34 made of wood and fastened to the base 24 with suitable screws and nails and glue. The downward, outward slope of the front left and front right primary sitting surfaces 22, 23 of the seat top 20 will be apparent from the equal-elevation lines 40.

In Fig. 6, is a perspective view of the sitting device 10 with double dashed lines 50 dividing the seat top's primary sitting surface into left and right side sections 46, and 48, respectively. Two secondary dotted lines 52, 52' divide the right and left side sections 46, 48 into right front sitting surface, a right rear sitting surface, a left front sitting surface, an a left rear sitting surface.

Taking the right side as an example, a model surface fit is calculated based on the right primary sitting surface; this determines an optimal fitted axis of a cylinder in the model, not shown, which represents the thigh in contact with the right primary sitting surface; the said axis is oriented at a substantially downward and outward angle; a normal plane to the said axis at the intersection between the model's sphere, which represents the buttock, and the model's cylinder, cuts the right primary sitting surface into front and rear portions as indicated by dotted lines 52. By this division, the characteristics of a thigh support region and a buttock support region of a seat can be defined without reference to the seat by a user. Light weight lines 60 show two circles 62, 63 indicating a cylinder of vertical axis 66 and orthogonal crossing lines antero-posteriorly 68 and laterally 70, for orientation; the upper circle 62 is centered on a point 72 within the right front primary sitting surface plane. "FHR" indicates a forward-horizontal ray 80 starting from a point 72 within the right front primary sitting surface plane. "LSS" indicates the line of steepest slope 82 within the front right primary sitting surface plane which passes through the endpoint of the forward horizontal ray 72. "O" indicates the outward angle 84 between the forward horizontal ray and a projection up to the horizontal plane of the line of steepest slope. "D" indicates the downward angle 86 between the horizontal plane containing the circle 62 and the line of steepest slope 82.

It is striking for a seat to have distinctly positive values for both "O" and "D" simultaneously, that is, to be designed for the user to fall off of it to either side or to the front. Yet after recognizing that the lower legs and feet, through the knees and upper legs, can provide actively weight-bearing support laterally within a sitting posture - in a cross-legged sitting posture - and can further also prevent forward sliding in a cross-legged sitting posture, utility cannot be denied for these seat shapes, which assist in and reduce the amount required of thigh supination and help to tilt the pelvis top-forward, enabling improved spinal posture. Having conceived the striking novelty of a support device for cross-legged sitting with distinctly positive values for both "O" and "D" simultaneously, a wide range for these values is claimed. Ranges are also claimed for similarly measured slopes for rear left, rear right, and entire primary sitting surface planes. Different users may prefer different values of "O" and "D" within these ranges, as also of the elevation of the primary sitting surface, depending on their size and various dimensions of flexibility and other support preferences, while receiving the benefits uniquely associated with the seat shape characteristics described.

Figs. 7-10 show front, rear, and side elevational views of a preferred embodiment fo the sitting device 10 The seat top 20 and base 24 comprising left and right members 30, 32, and cross-member 34 are visible in FIGS. 7, 8. The support members 30, 32, 34 in FIGS. 7, 8 provide lateral supports contacting the floor several inches to the side of the seat midline, leaving space in the front central area on the floor below the primary sitting surface, so the feet can be tucked under the front center of the seat and between the lateral supports.

The side elevations views shown in Figs. 9 and 10 show the front edge 26 lower than the rear edge 25. In this embodiment, the front edge 26 is approximately 3.5 inches from the support surface and the rear edge 25 is approximately 6.5 inches from the support surface. It should be understood however, that the heights of the rear and front 25 and 26 may be higher to accommodate taller and less flexible individuals.

Fig. 11 shows a top plan view of the sitting device 10 with equal-elevation (topo) lines 40 at a uniform vertical spacing (one quarter inch), and double-dashed reference lines 12-12, 13-13, 14-14, 15-15, and 16-16 situating the cross-sectional views in Figs. 12-16.

Figs. 12-16 each show a front elevational sectional view taken along lines 12- 12; 13-13; 14-14; 15-15; 16-16 in Fig. 11.

The foregoing describes just one embodiment of an invention for a support device for cross-legged sitting. In compliance with the statute, the invention described has been described in language more or less specific as to structural features. It should be understood however, that the invention is not limited to the specific features shown, since the means and construction shown, comprises the preferred embodiment for putting the invention into effect. The invention is therefore claimed in its forms or modifications within the legitimate and valid scope of the amended claims, appropriately interpreted under the doctrine of equivalents.

GLOSSARY

The following definitions shall apply throughout the specification and the appended claims unless stated otherwise.

The term, "sitting device ", denotes a sitting support device.

The term, "thigh supination", denotes that the top surface of the thigh rolls outward relative to its position in an upright sitting posture of thighs horizontal and feet directly below knees.

The term, "cross-legged sitting", denotes sitting with at least part of each foot disposed on the laterally opposite or crossed side of the mid-sagittal plane from the connected hip, with at least one knee bent more acutely than a right angle, with at least one thigh supinated at least 45 degrees, and with the side or front of some part of at least one lower leg and/or foot contacting a lower support surface.

Following are several technical definitions found necessary to describe the shape of a seat without reference to function. Users and their characteristics are removed from the basis of these definitions, and measurements and calculations derived from the properties of the device itself are substituted. The concepts of front and rear relative to a side of the sitting surface have received special attention because the thighs may also extend downward and outward at angles, so square and level assumptions cannot be made. Also the concept of a plane approximating a weight- bearing portion of the sitting surface is also developed here without reference to a user's characteristics. Functional interpretations are also given often to aid comprehensibility, but the following definitions can and are used without functional interpretation. No definition is necessary for frame of reference terms such as 'vertical' or 'horizontal', or for the midline of the seat.

The term, "sitting surface", relative to a seat, denotes a locus of points constituting the upper surfaces of the seat after the seat is compressed vertically by a weight of one pound per square inch distributed uniformly over the seat. It may be understood that the sitting surface is similar to the surface of the seat after it is compressed by a user sitting thereon.

The term, "primary sitting surface", denotes a portion of the sitting surface of a seat, that can stably support at least 150 pounds distributed uniformly thereon, that extends at least five inches antero-posteriorly, that extends at least seven inches laterally, that is a maximal contiguous region of the sitting surface bounded within a vertical range of 4 vertical inches and with its rearward edge. It may be understood that the primary sitting surface is the portion of the sitting surface intended to be located beneath, providing support for, and in contact with the user's upper thighs and buttocks.

The term, "secondary support surface", denotes a support surface below and at least partly in front of the primary sitting surface. It may be understood as the surface that supports a side or front of a foot or lower leg when sitting on the seat in cross- legged posture. It may, but need not be, understood as being the floor, since in an alternative embodiment the device may provide a secondary support surface means elevated higher than the floor.

The term, "forward", may be functionally understood as the direction a user faces when sitting on the seat, and can be defined without reference to function if the seat has a back (forward being the opposite direction) or if the seat provides special facilities for the feet on one side (being on the forward side), or if the seat is symmetrical rotationally or antero-posteriorly, one direction or side may be chosen arbitrarily as the forward direction or forward side and the forward direction is then in the direction of the forward side for the discussion. If the above criteria fail, then forward may also be assumed to be understood without definition based on inspection of the device.

The term, "rearward", denotes the opposite direction of the forward direction.

The term, "forward horizontal", denotes the direction of a ray with endpoint being the rearward-most point on the midline of the primary sitting surface of a seat and pointing horizontally in the direction of the projection of the forward-most point on the midline vertically into the horizontal plane containing said endpoint. It shall be understood any forward horizontal ray is parallel to and in the same direction as said ray but may have a distinct endpoint.

The terms, "left", and "right", when applied to the primary sitting surface, denote, respectively, the left and right half side of the primary sitting surface after it is divided by a vertical plane through the midline of the seat, when viewed facing forward.

The term, "model surface fit", relative to a right or a left primary sitting surface of a seat, denotes an optimal fit of a model lower surface to the right or left primary sitting surface. A model lower surface is characterized, parameterized, and placed within the geometry of the respective right or left primary sitting surface portion; then parameters of the model are varied in a deterministic and finite search procedure that establishes the parameter values providing a best fit between the model lower surface and the sitting surface. These parameter values are then available for reference as determinate values derived from the sitting surface portion. For concreteness using a simplified model, ignoring femur-head complexities, the model and its fit to a portion of a sitting surface is described as follows. The model refers to a sphere and a cylinder, the cylinder's axis intersecting the center of the sphere. The radius of the sphere may be 3.5 inches; the radius of the cylinder may be 3 inches and must be less than or equal to the radius of the sphere. The intersection of cylinder and sphere surfaces, considering the part of the cylinder only to one side of the center of the sphere, is a circle within a plane normal to the axis of the cylinder; the cylinder surface extending in that direction away from the sphere may be understood as a model of the thigh surface and its lower half as a model of the thigh's weight-bearing surfaces, and the sphere surface excluding the cylinder-cut section may be understood as a model of the buttock and its lower half as a model of the buttock's weight-bearing surfaces. The measure of fit between the model and a portion of a sitting surface is characterized by first establishing a set of corresponding points in the model and the sitting surface with their elevations, second by constraining the location of the center of the sphere, and third by searching out the best combination of values of three parameters over their ranges to find the optimal measure of fit to the right or left primary sitting surface. First the model and right or left primary sitting surface are projected into a horizontal plane; the intersection of the two projections is covered with a square grid of one-half inch between lines, and the set of grid intersections, each with its vertically aligned points in the model and in the portion of sitting surface, are the set of points in correspondence. The elevations of the model and sitting surface at each vertically aligned point are then established by measurement or calculation. Second, the sphere is placed within the geometry of the sitting surface portion. The center of the sphere is constrained to be located 3.5 inches laterally from the midline of the seat to the right or left side and 3.5 inches forward of a defined rear end landmark. If a seat back is present and includes a point on its forward surface at 3.5 inches above the primary sitting surface and 3.5 inches to the side of the seat midline, then the rear end landmark is the said point. If a seat back is not present, the rear end landmark is a point at the rearward edge of the right or left primary sitting surface at 3.5 inches to the side of the seat midline. Third, the search for the best fit of model to sitting surface portion is now described, starting with the search space parameters. The first parameter is the elevation of the center of the sphere within a range bounded at least by the lowest elevation of the primary sitting surface and by the highest elevation of the primary sitting surface plus 3.5 inches. The second and third parameters are the angles inward/outward and up/down of the axis of the cylinder as it extends from the sphere center forward of the lateral vertical plane that includes the sphere center. Each of these two angles is bounded within a range between -90 to 90 degrees. The measure of fit is the sum of the reciprocals of squared differences between elevations of corresponding points in the model surface and the sitting surface portion. This measure of fit grows as the model surface approximates the modeled surface. The global search is carried out by a large number, 1000, of local searches each starting from a random place in the parameter space and carrying out a step-wise, breadth-first, local, hill-climbing search procedure as follows.

Starting a step at a current set of parameter values, all small adjustments to the parameters are separately made, a degree of angle or a sixteenth of an inch, and the resulting measure of fit is separately calculated. Selecting particular adjustment, which makes the greatest improvement to the measure of fit, as defining the new current set of parameter values for the next step, this procedure is repeated until no improvement is achieved by any adjustment. At this point the search stops at a local maximum of the measure of fit associated with a set of parameter values. The best parameter values and measure of fit are updated if improved upon. After the specified number of searches is completed, the process stops and the result may be the globally optimal parameter values and measure of fit. Are defined the optimum values of the angles of the cylinder axis and the elevation of the center of the sphere for the model surface fit. It may be understood these angles and elevation approximately represent the location and orientation of a thigh and buttock of a user sitting upon the primary sitting surface.

The terms, "front" and "rear", when used to qualify either the right or the left primary sitting surface, denote the front and the rear portions of the respective half of the primary sitting surface after that half has been further divided by the plane containing the circle of the intersection of sphere and cylinder of the model surface fit to the right or left primary sitting surface of a seat. While this definition relies in no particular on a user's use of the seat, and therefore is not a functional definition, it may also be understood that the front left and front right primary sitting surfaces approximately represent the supporting surfaces for the thighs and the rear left and rear right primary sitting surfaces approximately represent the supporting surfaces for the buttocks, even if the thighs are not oriented axially in a forward horizontal direction, as being considered here. If this definition is rejected as irremediable, then "front" and "rear", when used to qualify either the right or the left primary sitting surface, shall denote the front and rear of the respective half of the primary sitting surface after that half has been further divided by a lateral vertical plane 3.5 inches forward of the rearward-most point of the primary sitting surface.

The term, "primary sitting surface design weight distribution", relative to a seat, denotes distributing 150 pounds proportionally across to a model weight distribution on the primary sitting surface.

The term, "model weight distribution on a primary sitting surface", denotes a weight distribution modeled separately and symmetrically on right and left sides of the primary sitting surface and further separately on front and rear portions of each side. Applying a square grid as in the definition of "model surface fit", points on the primary sitting surface portion corresponding to a grid intersection, receive a weight in proportion to the positive numerical values calculated in another model equation, using again a 3.5 inch radius sphere in the rear area and a 3.0 inch radius cylinder in the front portion, where the sphere's center is on the cylinder's axis at the boundary between rear and front. The points in the primary sitting surface portion which correspond to the points on the sphere receive a weight in proportion to the height of the sphere's upper surface above its center. The cylinder axis is angled downward at the slope at which the axis is one cylinder radius below the origin at the forward edge of the primary sitting surface or 12 inches horizontally from the sphere's center, whichever is closer, and the cylinder's axis angled to left or right using the

inward/outward angle established for the axis of the cylinder in the model surface fit to the respective right or left primary sitting surface. The points in the primary sitting surface portion which correspond to the points on the cylinder receive a weight in proportion to the elevation of the upper surface of the cylinder above the sphere's center. It may be understood that the model weight distribution on a primary sitting surface is approximately the weight distribution of an average user sitting on the seat.

The term, "sitting surface plane", when applied to any part or all of a sitting surface, denotes the plane closest to the respective part of the sitting surface, where 'closest plane' is defined mathematically as that plane which minimizes a weighted least squares (vertical) distance summed over the respective part of the sitting surface, wherein the (squared) vertical distance at each point is weighted by the value of the model weight distribution on the primary sitting surface portion. It may be understood that the sitting surface plane approximately represents the weight-bearing portions of the part of the sitting surface. It may be understood that non-weight- bearing points on the respective part of the sitting surface are ignored in determining the closest plane. It may further be understood that points bearing the most weight per unit surface area will have the greatest influence in determining the closest plane.

The term, "center of a primary sitting surface", denotes the weighted average of the points in the primary sitting surface, where each point is weighted by the model weight distribution on the primary sitting surface or by zero for points outside the model weight distribution.

INDUSTRIAL APPLICABILITY

This invention has application in the furniture and personal meditation industries.

Claims

1. A sitting device to support sitting cross-legged on a support surface, comprising

a) a saddle- shaped seat with a rear edge, two curved lateral edges, and a curved front edge and a bottom surface, said rear edge elevated above said front edge, said seat also includes a sloped center region that extends downward from the rear edge to the front edge and two symmetrical side sections that curved downward and curved outward from and on opposite sides of said center region, said center region and said side sections configured to support a user sitting on said seat with his or her buttocks positioned adjacent to the rear edge and aligned over the center region and with his or her thighs; and,

b) a seat base connected to said bottom surface on said seat, said seat base configured to support said seat above a support surface to elevate said rear edge above the front edge thereby enabling a user to sit on said seat with his or her buttocks positioned adjacent to the rear edge and aligned over the center region and with the user's thighs extending downward and outward, and then bending the knees in front of the front edge to allow a user to cross his or her legs.

2. The sitting device of claim 1 , wherein the rear edge of said central region of said primary sitting surface is elevated approximately 12 inches above a support surface and said front edge if said central region is elevated approximately 6 inches above a support surface.

3. The sitting device of claim 1, wherein the rear edge of said central region of said primary sitting surface is elevated approximately 6 inches above a support surface and said front edge if said central region is elevated approximately 3 inches above a support surface.

4. A device to support sitting cross-legged, comprising

a) a seat with a primary sitting surface means, said primary sitting surface means having a primary sitting surface with a center region elevated between about two to sixteen inches above a secondary support surface, whereby the buttocks may be raised above the feet, said primary sitting surface also having right and left primary sitting surfaces, said right and left primary sitting surfaces each having a front and a rear primary sitting surface and said front and rear, right and left, primary sitting surfaces each having a sitting surface plane, said front primary sitting surface planes being sloped out of the horizontal and having a line of steepest slope disposed at an angle between 10 and 135 degrees outward from a forward horizontal ray when said line of steepest slope is projected into the horizontal plane and said line of steepest slope further being disposed at an angle between 3 and 70 degrees downward from the horizontal plane, whereby the thighs can be assisted in supinating to achieve greater comfort and duration in cross-legged sitting and whereby the hips can be supported in tilting top-forward to support a beneficial core posture, and whereby the upper thighs can be supported while sloping downward and outward in a cross-legged sitting posture; and,

b) a seat base means being operatively connected with the said primary sitting surface means, the said seat base means being located below the said primary sitting surface of the said primary sitting surface means, providing support for weight coming through the said primary sitting surface means, and assisting the said primary sitting surface means to maintain its shape under compressive forces, and the seat base means being configured to elevate and stably hold the center of the said primary sitting surface at an elevation two to sixteen inches above a lower, secondary support surface, which may be but need not be the floor, and

said seat base means being configured to elevate and stably hold the center of the said primary sitting surface at an elevation above an underlying support surface in the environment of and beneath said seat base means.

5. The sitting device of claim 4_S wherein the said front left and front right primary sitting surface planes each have a line of steepest slope disposed at an angle greater than 10 and less than 90 degrees outward from a forward horizontal ray when said line of steepest slope is projected into the horizontal plane, whereby the upper thighs can be supported in sloping downward, outward, and forward and whereby the thighs can be assisted in supinating so as to achieve greater comfort and duration in cross-legged sitting and whereby the hips can be supported in tilting top-forward in a cross-legged sitting posture.

6. The sitting device of claim 4, wherein the rear left and rear right primary sitting surfaces planes are sloped out of the horizontal with a line of steepest slope disposed at an angle between 10 and 90 degrees outward from a forward horizontal ray when said line of steepest slope is projected into the horizontal plane and said line of steepest slope further disposed at an angle between 3 and 70 degrees downward from the horizontal plane, whereby the hips can be supported in tilting top-forward in a cross-legged sitting posture.

7. The sitting device of claim4, wherein the entire primary sitting surface has a primary sitting surface plane, said primary sitting surface plane being sloped out of the horizontal and having a line comprising the intersection of said plane with the vertical plane containing the midline, said line being disposed at an angle sloping downward at an angle greater than zero measured between the said line and a forward horizontal ray with endpoint within the said line, whereby the hips can be supported in tilting top-forward in a cross-legged sitting posture.

8. The sitting device of claim 4, wherein the base is disposed to leave unobstructed area below the central six inches of the front three inches of the primary sitting surface for three inches immediately above the lower secondary support surface, whereby the heels can be tucked by a sitting cross-legged upon the device.

9. The sitting device of claim 4, wherein the device also comprises a seat back.

10. The sitting device of claim 4, wherein the floor is the secondary support surface for the lower legs and feet and the elevation of the center of the primary sitting surface is between two and sixteen inches above the floor, whereby the sides or fronts of lower legs or feet may be in contact with the floor while the buttocks are on the seat.

1 1. The sitting device of claim 4, wherein the primary sitting surface is elevated 12 inches or more above the floor and wherein support means are provided above the floor for the fronts or sides of the lower legs or feet to contact when disposed in a cross-legged sitting position.

12. A method of cross-legged sitting comfortably and for extended durations comprising the steps of:

a) selecting and providing a seat device that includes;

i) a primary sitting surface means,

1) the center of the primary sitting surface means being elevated between about two to sixteen inches above a secondary support surface, whereby the buttocks may be raised above the feet to an elevation comfortable for the user;

2) the primary sitting surface means having right and left primary sitting surfaces, the said right and left primary sitting surfaces each having a front and a rear primary sitting surface and each said front or rear, right or left, primary sitting surface having a sitting surface plane, said front primary sitting surface planes being sloped out of the horizontal and having a line of steepest slope disposed at an angle between 10 and 135 degrees outward from a forward horizontal ray when said line of steepest slope is projected into the horizontal plane and said line of steepest slope further being disposed at an angle between 3 and 70 degrees downward from the horizontal plane;

and,

ii) a seat base means configured to elevate the center of the primary sitting surface two to sixteen inches above a secondary support surface and said seat base means being operatively connected with the primary sitting surface means, being located below the primary sitting surface, providing support for weight coming through the primary sitting surface means, and assisting the primary sitting surface means to maintain its shape;

b) positioning said sitting device at a desired location upon an underlying support surface in the environment of and beneath the seat; c) sitting with knees apart upon the said primary sitting surface at an elevation between about two and sixteen inches above the secondary sitting surface, with knees apart;

d) selecting one side's leg to go first and the other side's leg to go second; e) supinating said first leg's thigh to a comfortable degree assisted by the downward, outward slope of the said side's front sitting surface;

f lowering said first leg's knee to an elevation that disposes said leg's thigh axially in a downward outward orientation, whereby said leg's upper thigh is supported comfortably upon the said downward and outward sloping, front side primary sitting surface;

g) resting a front or side of the same-side lower leg or foot upon a secondary support surface;

h) supinating the said second leg's thigh to a comfortable degree assisted by the downward, outward slope of that side's front sitting surface;

i) lowering said second leg's knee to an elevation that disposes said leg's thigh axially in a downward and outward orientation, whereby said leg's upper thigh is supported comfortably upon the said downward, outward sloping front side primary sitting surface;

j) resting a front or side of said second leg's lower leg or foot upon either the secondary support surface or the said first leg's lower leg or foot;

k) transferring weight through the thighs to knees, lower legs or feet limiting their downward and outward sliding spread, whereby the thighs are enabled to provide lateral support while the said primary sitting surface means and the said base means provide vertical support centrally from below;

1) maintaining the hips tilted top-forward whereby the higher curves of the spine can be easily maintained in a easeful, erect, and balanced posture; and, m) adjusting the legs, straightening one leg , reversing order between the legs, or getting up from the seat, when sitting becomes uncomfortable or painful, whereby discomfort, pain, and injury are prevented and safe cross-legged sitting and device use is ensured.