AU595304B2 - Tilting seat - Google Patents

Description

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V'ATENT ACT 1952 COMPLETE SPECIFICATION (Original) FOR OFFICE USE Class Int- Class Application Number: Lodged: 7/73~3~~7 Complete Specification Lodged: Accepted: Published: Priority: Relatfed Art: 3ecuoa 4 t z

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Name of Applicant: Address of Applicant: Actual Inveitor (s) ERGOFORM T.NC. 685.Avenue Meloche, Dot~al, Quebec, CANADA H&P 2S4.

Bernard SHALINSKY Christopher J. SCRASE Raymond MITCHELL DAVIES COLLISON, Patent Attorneys, 1 Little Collins Street, Melbourne, 3000.

4 4 Address for Service: Complete specification for the invention entitled: "TILTING SEAT" The following statement is a full description of this invention, including the best method. of performing it known to us -I

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4 tI 14 I I fi 449,4 9. II If I 4191 f t 15 20 BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to seats, and particularly to a tlilting seat.

2. Description of the Prior Art It is estimated that between 65 and 75% of days lost from work is due to back ailments. More and more, particularly with the development of computers, the worker is required to spend a greater amount of time sitting at a work station. On the other hand, most conventional chairs or seating arrangements presently utilized in the workplace require the user to hunch forward in order to work at a desk or table.

By hunching forward, the stress on the lumbar region is increased by 300%, resulting in premature disintegration of the lower discs and vertebral arthritic degenera tion.

In recent years, a myriad of "ergonomically" designed chairs have been developed, all of which use a backward inclined seat. Although these chairs have proved to be more "comfortable" in the reclined posi- 25 tion, the user is still obliged to hunch forward in order to work at a desk or table. By hunching forward, the stress on the lower spine (lumbar region) is increased some 300%; the result bPeing a premature disintegra '-ion of the lower discs and vertebral arthritic degeneration.

Recent research has brought about a greater comprehension of the function of the lumbar sp,,Ilne and -2- -4

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*551 to I brings into question the basic traditional seated work position. Based on the sound physiological evidence as provided by internationally recognized experts such as Doctors Keegan, Nachemson, and Grandjean, the ideal seated work posture should maintain a minimum curve in the lower spine (lordosis). This position allows the efficient support of the body weight, with the least amount of work and stress. In most cases, a person using a backward inclined seat, eradicates the lordosis by leaning forwar.d to work. The forward inclined seat compensates for this necessary movement towards the work surface by allowing the person to tilt his whole body forward, thus eliminating the rounding of the back and the subsequent loss of the lordotic curve. The 15 forward incline makes it possible for a person to maintain this critical lordosis of the lumbar spine while performing many different tasks.

Recent research has brought about a greater understanding of the structure and function of the lumbar spine and brings into question the basic traditional seating and the position of the user. According to physiological evidence, the ideal seated work posture should maintain a minimum lordotic curve in the lower spine. This position allows the efficient support of the body weight with the least amount of stress.

-Sf iMARY 0F THE ItNVENTION.i It is an aim of the present invent to provide a seat which would be comifo le in a rest position, that is, in a no sitting position, and which would tilt ward with the user as the user advance sImself to the work table, thereby generally n h ei b-ik peitonn with clsiht 3 4- 1 According to the present invention there is provided a 2 seat having a base, a stem having upper and lower ends, the 3 lower end of said stem being pivotally mounted on the base 4 and tiltable relative to the base only about a transverse pivot axis at the base, a buttocks support having a centre 6 portion, said support mounted in a cantilever manner on the 7 front of the stem such that the upper end of the stem 8 projects above the buttocks support, the stem exterding 9 rearwardly over the bas, and adapted to pivot in an arc of movement, means for limiting the pivot arc of movemrit in a 11 vertical plane normal to the transverse axis between a rest 12 position with the stem at an acute ungle behind a vertical 13 plane taken through the transverse pivot axis, a center of 14 the buttocks support being substantially near said vertical plane and a forward position when the stem is adjacent but 16 behind the vertical plane and the center portion of the 17 buttocks support is forward of the vertical plane.

18 It has been found that in a preferred embodiment the 19 stem in its rest position would be supported at an angle of 21 from the vertical plane and at an angle of 90 from the 21 vertical plane in its forward position such that the total 22 pivotal arc of travel of the stem is 12°.

-o 23 24 26 27 28 .TT 29 900109.araspe0O ;71755cl.

Thus, this construction allows the user to sit back on the seat or chair when not working over a work desk or table. However, when the user moves forward to work over the table, the buttocks support and the stem, would merely follow the usex' and tilt forwird allowing the user to maintain a proper erect position with the proper lordotic curve in the lumbar region.

It is believed that this would allow the user to work in a much more comfortable position with considerably less stress on his back. The phenomenon is similar to the natural inclination, particularly with youngsters, to sit on the edge of their chair while working over a table. It has also been found, in studies, that it is .important to maintain a relatively open or olbtlase angle between the thighs and the upper body. With the embodiments described herein, this obtuse angle can be maintained between the thighs and the upper body even when the user is working over his work table due to the tilting and inclination of the buttocks support on the seat. using an ordinary chair, even if moving the chair forward under the table while working over the table, the thi~hs assume a closed or acute angle with respect to the upper body when the user is hunched over 6 the table.

BRIEtF DESCRIPTION OF THE DRAWINGS Having thus generally described the nature of the invention, referqnce will now be made to the accompanying drawings# showing by way of illustration, a pr~eferred embodiment thereof, and in which: Figure 1 is a perspective view of one embodiment of the seat in accordance with the present invention; Figure 2 is a side elevation of the seat shown in Figure 1; Figure 3 -is a front elevation of a seat showing another embodiment of the present invention; Figure 4 is a vertical cross-section taken along line 4-4 in Figure 3; Figure 5 is a fragmentary enlarged crosssection taken along line 5-5 in Figure 1; Figure 6 is an enlarged fragmentary crosssection taken along line 6-6 of Figure 3; Figure 7 is a fragmentary top plan view of a detail of the present invention; Figure 8 is a schematic view showing the different positions of the r~eat; Figure 9 is a front elevation of the base in accordance with an embodiment of the i{ present invention; Figure 10 is a side elevation of the base shown in Figure 9; Figure 11 is a vertical cross-section taken through a detail similar to that shown in Figure 5, of another different embodiment thereof; Figure 12 is a fragmentary enlarged crosssection of a detail similar to that shown in Figure 5 but of a different embodiment thereof; Figure 13 is an enlara-d far,,entary sectional view along line 13-13 of Figure 12; 6 g a

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~I Figure 14 is a bottom plan view of the base shown in Figure 9; Figure 15 is a cross-sectional view taken along line 15-15 of Figure 14; and Figure 16 is a cross-sectional view, similar to Figure 15, but showing a detail thereof in a different operative position.

DESCRIPIION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, there is shown in Figures 1 and 2, a first embodiment of a seat including a base 12, a stem 14, and a buttocks support 16.

The base 12 and stem 14 in this embodiment are integral, and as shown in Figure 2, the base 12 describes an acute angle with the stem 14 extending over the base 12 at an angle of 71°. The buttocks support *16 is made of molded plastics material and may have a shell 18 and a soft interior 20. The buttocks support 16 is pivotally mounted at 22 on a bracket 24 which can be adjustably located along the longitudinal axis of the stem 14.

The stem 14 is in the form of an elongated member having a track 26 in the form of an elongated slot having a T-shaped cross-section. As shown in Figure 5, the bracket 24 includes a carriage 28 sliding in the track 26. The carriage 28 is provided with a series of spaced-apart apertures 30 with each aperture having a radial flange 32. The back of the stem 14 is provided with a bore 34.

A locking pin 36, including a rounded knob 38 and an L-shaped pin 40, passes through the bove 34.

7 c w, i.~he locking pin 36 also includes a spring 42 in the recessed part of the bore 34. The L-shaped pin is adapted to engage in apertures 30 of the carriage 28 to lock the carriage in a selected position.

When it is r~quired to release the carriage 28 from a given position, the carriage must be moved upwardly slightly to disengage the L-shaped pin from the flange 32. The pin 40 is then retracted against the spring 42 into the recessed portion 34, and the carriage 28 is then free to move to a new adjusted vertical position. The spring 42 will be effective to move the locking pin 40 to a new aperture 30 on the carriage 28 when such aperture is aligned therewith.

As also seen in Figure 5, the seat 16 is pivotally mounted on the pivot shaft 22 in the bracket 24, and the pivoting movement of the seat is restricted by a limit pin 44 which i& fixed to the seat J,6 and travels in an arcuate slot 46.

The stem 14 merges with the base 12 foz'ming an acute angle with reference to the embodiment in Figure Iand 2, and the angled surf ace 48 formed at theforardpar ofthe base 12 is rounded, allowing the seat to be pivoted or tilted along the rounded surface 48 which defines a tilting axis of the seat As shown in Figures 1 and 2, the seat 10 is illustrated in a rest position. A user may sit on the seat in this position and be comfortably erect. If the user wishes to move forwardly to 4 work position within the arc between the position shown In full lines and that, shown in dotted lines in Figure he need merely move bimselZ forward over a table), and the seat 10 will tilt ;forward with him. In the. case of 8 i the embodiment shown in Figures I. and the seat will tilt about the axis defined by the surface 48, moving the center of gravity of the user from a position over or behind the vertical plane containing the axis of tilting to a position shown in dotted lines in Figure 2 where the buttocks support 16 is well ahead of the vertical plane so defined. The user's forward movement also brings the center of gravity tb,:reof beyond the vertical plane including the tilting axis, and the natural inclination to maintain an open obtuse angle f of the thighs to the upper body will cause the buttocks support 16 to pivot aboait the shaft 22 through a possible 'fit angle d of 450. The angle f may vary from 1300 in the rest position to 1050 in the forward position. Thus as seen in Figure 8, when the seat is tilted forwardly, the lordotic curve in the lumbar region of the spine is The tilting of the seat will normally be through a~n arc a in the drawings which may be in the rea of 200, although this arc may vary 50 either way it is also seen that if the user were to lean back filom the tbible, the seat 10 Will, because of its ,stable position, tilt back to a rest position as shown in Figures I and 2 in fuV2. line&.

2$ Another embooimient oi. the seat is sqhown in Figures 3, 4 am:d 6, in which the base 50 is in the form of a turntabl.e, including a sub-base The stub-base 51l may have a rubber or soft plastic molded. covering 52 over the edge of a skirt .84 extending from an annulus 56 which is in a horizontal plane. A lower bearing race 58 is mounted to the annulus 56 and supports ball bearings 60 as shown in Figure 6. An, 9 upper base portion 62 is provided which mounts an upper race 64 which cooperates with the lower race 58 and the ball bearings 60.. The upper base portion 62 has an overhanging skirt 66. The upper base portion 62 mounts a pair of upstandingj journals 68 and 70 which receive an arcuate lower member 72 of the stem 74. The journals have a rearward stop 76 and a forward stop 78 which limit the pivoting or tilting movement of the stem 74 relative to the base. The arc may be limited to 20 0. The arc, identified by the letter c, is actually 12 0with the forward position at 9 0from the vertical plane through the pivot axis and the itest position at 210 from the vertical plane.

In the preferred embodiment, the stemn 14 does not pass the ver~tical plane through the pivot axis of the stem, but rather its movement terminates in a forward position slightly behind the vertical plane.

As can be seen, however, the buttocks support 1.6 in the rest position has its center position in the vertical plane or just slightly behind the vertical plane, while in the forward position, the buttocks support 16 is in front o( the verLical plane. The user of the seat as described. supports its full weight on the seat both in I the rest position and the forward position, as shown in 2$ Fig'~re of the drawings.

Thus, in the embodiment shown in Figures 3 and 4, the user has the advantage of the tilting seat previously de'-Icribed and may rotate the seat on the turntable.

Figures 7 and R1 represent the effect on the body and in particular as represented by a s)kelton diagram in these drawings. The buttocks support 1.6

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is provided with an enlarged mound 80 forward and central of the support which influences the thigh bones to rota'-- outwardly in the direction of the arrows shown in Figure 7, to provide a more ieural and comfortable S seating. Figure 8 represents the position of the lumbar region of the spine in both the rest position and the tilting .position of the seat A different embodiment of the base is illus- Crated in Figures 9, 10, and 14 through 16. The base 110 includes a turntable portion 112 and an upstanding pedestal 114. As shown in Figure 10, the Fedestal 114 includes a slot defined by a pair of abutments 116 and 118 which limit the pivoting arc of travel the stem 14. The stemi 14 includes two ears 120 which aire journaled on a pivot shaft 122. The abutment surface 116 is provided with a bellows type resilient device~ 124 while t ie abutment 118 is provided with a re~ailient stop 126. The base, as best shown in Figures 14 through 16, includes a sub-framc 128 mounted by means of a rubber or plastic suspension device 1,30 to the shell 132. The shell 132 includes a skirt 134 surrounding jthe periphery of 1 the sub-frame 128, The sub-~frame 128 is provided with a series of openings 136. A leg 138 is integrally molded at 140 to the sub-frame 128 or may be otherwise fixed, thereto. The other end of the leg 138*, includes a head 142, defining a spherical socket mounting a ball 144. The legs 138 are chosen of a material and size such that when there is no weight on the seat, the'balls 144 are in conta<,'t with the ground or f loor, but as soon as a weight is applied to the.

seat, the legs 138 will flex to allow the sub-frame 128 to rest; on the floor and thereby prevent the rolling movement of the base.

Referring now to Figures 12 and 13, there is shown a stem 14 having a carriage 1,50 sliding in the track 152. The carriage 150, which is similar to carriage 28, mounts a bracket 154. A pivot shaft 156 is fixed tu the bracket 154, and 4 pair of downwardly extending ears 158 are pivotally wi-o1nted to the shaft 156. The ears 158 mount the shell 160 of the buttocks support. A small resilient pad 162 is provided on the upper surface of the bracket 154 to act as a stop for the rearward pivoting movement of the buttocks support 16.

Figure 11 illustrates another embodiment of the locking pin 36. The embodiment in Figure 11 has reference numerals raised by 200 which correspond with the numerals in Figure S. The carriage 228 in this embodiment is made in the form of a U-shaped channel with apertures 230 provided on one side thereof, The carriage 228 slides in the track 226. The locking pin 236 includes an L-shaped pin 240 moving in a sleeve 241 against the spring 242. A pin 244 acts as a forward limit for the pip 240. The ball or knob 238 is retained on the pin 240 by means of a ball retainer nut 246 fixed to the pin 240. The sleeve 241 includes flanges 24: on the interior of the track 226, as illustrated.

The operation of the locking pin 236 is thz s alm as thei locking pin 36.

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Claims (8)

1. A seat having a base, a stem having upper and lower ends, the lower end of said stem being pivotally mounted on the base and tiltable relative to the base only about a transverse pivot axis at the base, a buttocks support having a centre portion, said support mounted in a cantilever manner on the front of the stem such that the upper end of the stem projects above the buttocks support, the stem extending rearwardly over the base and adapted to pivot in an arc of movement, means for limiting the pivot arc of movement in a vertical plane normal to the transverse axis between a rest position with the stem at an acute angle behind a vertical plane taken through the transverse pivot S axis, a center of the buttocks support being substantially near said' vertical plane and a forward position when the stem is adjacent but behind the vertical plane and the I center portion of the buttocks support is forward of the vertical plane.

2. A seat as defined in claim 1, wherein the buttocks support is pivotally mounted on a bracket mounted to the stem, and means are provided for limiting the pivoting movement of the buttocks support about an axis parallel to the transverse pivot axis of the stem to the base in an arc limited between a first and second position.

3. A seat as defined in claim 2, wherein the buttocks support is adjustable in height relative to the stem, by *I means of a track provided on the stem and sliding track t .4 follower means provided on the bracket of the buttocks 0OO109 *ruue.o25,71755c1, ;Iy AIIf M MlIW W M W II~ y 'I Ml f 1 1 1 i r 14 0e. 441 4a '9 4 4 4 44 4 44 4* S4 4 4,,c 444444 support, and locking means being provided for locking the track follower at a selected height of the buttocks support on the stem.

4. A seat as defined in claim 2, wherein the buttocks support has a limited pivoting arc within the range of A seat as defined in claim 1, wherein the arc of movement of the stem between the rest position and the forward position is within

6. A seat as defined in claim 5, wherein the are of movement of the stem is between 210 and 90 from the vertical plane.

7. A seat as defined in claim 1, wherein said base includes a first member having a peripheral floor engaging edge, cantilevered resilient members mounting floor engagement wheels, the resilient cantilevered members being such that when there is no load on the buttocks support of the seat, the wheels are in contact with the floor and the floor engaging edge is spaced from the floor allowing the seat to be moved on said wheels, and when a load is borne by the buttocks support, the additional weight overcomes the resilient cantilevered members such that the peripheral edge of the base is in contact with the floor to thereby arrest the seat in a given position.

8. The seat as claimed in claim 7 wherein the wheels are in the form of roller balls mounted in a socket at the end of the cantilevered members.

9. The seat as claimed in claim 7, wherein the base includes a sub-frame which is circular and "the peripheral edge thereof has a circular locus; the resilient 900,09, arsspe.025,71755cl, -p. i ii e r cantilevered members extending radially from an inner portion of the sub-frame and extending outwardly towards the edge, said cantilevered member being regularly spaced so that the seat is completely supported by the wheels when the buttocks support is free of any addit'--l load such that the seat can be moved on the floor, freely in any direction. A seat substantial as hereinbefore described with reference to any one of figures 1 to 16 of the accompanying drawings. Dated this 9th day of January, 1990. o *o 00 00 0 O L 0 '0 o *o 0a 0 0 0 0: P O DAVIES COLLISON Patent Attorneys for ERGOFORM INC. 9ool9arsspe,025,11 7 5 5 cl