Posture chair

Feb. 9, 1943.

2,310,366

F. B. HARMAN

POSTURE CHAIR

Filed June 24, 1939

Sheets-Sheet 1

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Feb. 9, 1943. f. b. harman 2,310,366

POSTURE CHAIR

Filed June 24, 1939 2 Sheets-Sheet 2

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Patented Feb. 9, 1943

2,310,366

UNITED STATES PATENT OFFICE

2,310,366

POSTURE CHAIR

Frank B. Harman, Grand Rapids, Mich.

Application June 24, 1939, Serial No. 280,959

Claims. (Cl. &lt;155—115)

This invention relates generally to posture chairs and specifically to a type of posture chair in which the back and seat are relatively adjustable.

It is the purpose of posture chairs of the type described to provide adequate and proper support for the back and legs of a person seated in the chair. Such support is only adequate and proper when the seat of a chair is of such a length as to offer support for the entire upper part of the legs and when the height of the back of the chair is sufficient to support the person in the chair at the proper point along the spine. It is known that a tall person requires a greater back height and a greater seat length than does a short person, for the reason that a tall person generally has a longer body trunk and correspondingly longer upper leg portions. Furthermore, I have found that the ratio of the difference in back height required for any two normal people of different height to the difference in seat length required for the same two people is substantially constant.

It is the principal object of this invention to provide a posture chair of the type described wherein the back height and seat length of the chair may be simultaneously increased or decreased. It is another object of this invention to provide a posture chair of the type described wherein the ratio of the increment of change in the back height to the increment of change in the seat length is substantially constant.

It is still another object of this invention to provide a posture chair of the type described wherein the back height and seat length of the chair may be simultaneously increased or decreased by a single manual control operable by a person seated in the chair.

It is a further object of this invention to provide means adaptable to posture chairs of the type described fulfilling all of the above-named objects.

Other objects and advantages will be understood from the following description of the two possible embodiments of my invention.

In the drawings—

Figure 1 is a fragmentary elevation, partly in section, of an embodiment of a posture chair of my invention showing in detail means for effecting movement of the back and seat of the chair;

Figure 2 is a section taken on the line 2—2 of

Figure 1;

Figure 3 is a section taken on the line 3—3 of

Figure 1;

Figure 4 is a section taken on the line 4—4 of Figure 1;

Figure 5 is a detail, partly in section, showing a modification of the means illustrated in Figure 1; and

Figure 6 is a fragmentary section taken on the line 6—6 of Figure 5.

The posture chair illustrated in Figure 1 has a seat 10, a back 11 and a base 12. The seat and the back are supported by adjusting means which includes a head or frame 13 supported above the base 12 by a threaded spindle 14. The spindle extends downward from the head 13 and is slidably journaled in the base 12. The spindle is maintained at a desired level in the base by a plate-nut 15 supported on the base and threadedly engaging the spindle.

The chair described may be modified in many known ways. For example, the head 13 may be supported on a fixed base rather than the swivel type described, or the adjusting means may be only connected to the back and seat; the chair may have arms and a foot rest; the seating portions of the chair may be upholstered or plain, and many other such modifications may be made.

In one embodiment of the chair, the adjusting means comprises the head or frame 13 which consists of an elongated substantially U-shaped, member (see Fig. 4) having a yoke portion 18, side limbs 19, and a horizontally extending channel member 26. The channel member is secured through its flanges 21 and 22 to the head 13 by rivets 23 or other suitable means at a point sufficiently distant from the ends of the side limbs 19 to provide stubs 24 and 25. Slidably mounted on the stubs 24 and 25 is a sled-like bracket 26 which carries the seat 10.

The sled-like bracket 26 consists of oppositely disposed angle members 27 and 28 having one edge slidably engaging the top and the other edge engaging the outside surface of the studs 24 and 25 respectively. At each of the ends of the angle members 27 and 28 offset in an upwardly direction are apertured feet 29 to which is fixed the seat 10 by screws 30 or other suitable means.

In order to prevent the bracket 26 from disengaging the studs 24 and 25, a channel plate 32 is placed around the angle members, and its flanges are secured to the side limbs 19 by the rivets 23 or other means. The plate 32 slidably engages the outside surfaces of the angles 27 and 28 and thus insures the stability of the seat 10 relative to the head 13.

Rigidly secured to the head 13 at the outer end of the channel member 20 by suitable means is a

2,310,368 substantially vertical guide plate 33. This plate has parallel vertical edges 39 and 35 which are correspondingly angularly disposed to the central portion of the plate.

Slidably engaging the edges 34 and 35 of the guide plate 33 is an arcuate yoke 36 to the ends of which are secured parallel bars 37 for supporting the back ί I. At the middle portion of the yoke are a pair of oppositely disposed, oblique angle irons 38 each having one of its limbs 39 fixed to the yoke 36 by rivets 39a and the other of their limbs 40 slidably engaging the outer surface of the vertical edges 34 and 35 of the guide plate 33 (see Fig. 3).

Rotatably mounted on the guide plate 33 and on the channel member 20 of the frame 17 are screw shafts 4i and 42 having threaded portions 43 and 44 respectively. The screw shaft 4i is journaled through an apertured lug 45 which is secured to the central portion of the channel member 20 by rivets 46 and threadedly engages a nut 47 secured to a cross angle bar 48 which connects the two angle members 27 and 28 of the bracket 26. The screw shaft 42 is journaled through a pair of apertured lugs 49 which are secured at the top and bottom of the central portion of the guide plate 33 by screws 50 and threadedly engages, intermediate the lugs, a nut 51 which is secured to the central portion of the yoke 36 by screws 52. The screw shafts are rotatably connected by bevel gears 53 and 54. The gear 53 fits over the right hand end of the screw shaft 41 and is fixed thereto by a pin passing through the sides of the gear collar and the shaft 41, as shown. The bevel gear 54 is fixed to the screw shaft 42 and is positioned so as to mesh with the gear 53. Stop collars 55 and 56 are fixed on screw shafts 41 and 42, respectively, for preventing longitudinal movement of the shafts with respect to their supporting members.

From the above description of the adjusting means, it is seen that a rotation of either screwshaft 41 or screw shaft 42 by suitable means will effect simultaneously a linear movement of the bracket 26 carrying the seat 10 along the studs 24 and 25 of the head 13 and a movement of the yoke 37 carrying the back I! along the edges 34 and 35 of the guide plate 33.

As an illustration of one such means, there is provided a bevel gear 58 which is fixed to the screw shaft 4 ί and which is meshed with a second bevel gear 59. The gear 59 is fixed to the end of a rotatable rod 60.

The rod 60 is journaled in a hub-like bearing 61 which is formed in one of the side limbs 19 of the head 13. A suitable hole 62 is cut in the flange 22 of the channel 20 to allow for the bearing. There is also a suitable hole 63 in the channel 32 to permit the rod 60 to pass freely therethrough. The rod is prevented from longitudinal movement in the bearing by stop collars 64 and 65. Fixed to the outer end of the rod 60 is a handle 66 by which the entire adjusting mechanism may be operated by a person seated in the chair.

It will readily be seen that a rotation of the handle 66 in one direction will, through the cooperation of the bevel gears 58 and 59, produce a corresponding rotation of the screw shafts. This rotation of the screw shafts will produce a linear movement of the seat and the back since these threadingly engage the screw shafts in the above described manner. It is therefore only necessary to provide the screw shafts with threads that will cause simultaneously an upward movement of the back and an outward movement of the seat, and, then, if the handle 66 is rotated in the opposite direction, there will be simultaneously a downward movement of the back and an inward move5 ment of the seat. In Figure 1 the position of the seat and the back when the chair has the greatest seat length and back height is indicated by the broken line illustration of the seat and back, and their supporting brackets.

When it is desired to lock the adjusting means in order to prevent the position of the seat and back from being altered, there is provided locking means in cooperation with the guide plate 33 and the yoke 36. The locking means comprises a 15 handle 67 having a threaded stem 68 which engages an extension 69 of the limb 39 of one of the angle irons 38 which are secured to the yoke 36. The end of the stem 68 abuts the yoke 36 so that by turning the handle 67 in one direction the ex20 tension 69 moves away from the yoke, causing part 38 to rotate about the rivet 39a, which may be sufficiently loose for this purpose, and the limb 40 is thus pressed tightly against the edge 34 of the guide plate 33. This increased pressure be25 tween parts 40 and 34 creates sufficient friction to prevent any movement of the mechanism by a rotation of the handle 66.

Another embodiment of a chair of this invention may have an adjusting means of the con30 struction illustrated in Figures 5 and 6. Figure 5 is a section similar to that of Figure 1 for the previously described embodiment.

Said adjusting means is carried by a generally U-shaped head or frame 70 having partially off35 set side limbs 71 that flare at their ends and a yoke portion 72 from which extends a spindle 15' similar to the previously described embodiment. Fixed by rivets 73 to the ends of the side limbs are a pair of angle irons 74 having feet 75 to which is 40 attached the seat in the manner previously described. Said rivets 73 also serve to secure a channel member 76 to the ends of the side limbs 71 to form a part of the head 70.

On the rear end of the channel 76, there is 45 fixed by rivets 77 a guide plate which, because of its substantially identical construction to the guide plate described above, is numbered 33', having the angular edges 34' and 35'. The plate 33' is secured to the channel 76 preferably at an angle 50 of approximately forty-five degrees (45°) with the horizontal.

The guide plate 33' slidably supports the back in the same manner as in the above described embodiment, and the parts are so num55 bered that reference may be made to the previous description. It is to be noted, however, that the bars 37' which carry the back are joined with the yoke 36' in a manner which permits the back to assume a vertical position.

In order to rotate the screw shaft 44', there is provided gearing consisting of a miter gear 78 fixed to the lower end of the screw shaft and a miter pinion 79 meshed with the miter gear and fixed on the end of a rod 80.

The rod 80 is journaled in bearings 81 and 82 which may be integral with the head 70 or mounted thereon. The rod preferably extends forward and upward so that a handle 83 which is fixed to the outer end may be readily accessible 70 to a person seated in the chair. The rod 80 and screw shaft 44' are prevented from relative longitudinal movement by the action of the stop collars 84 and 85 and their respective gears.

It will be seen that a rotation of the handle

83 by a person seated in the chair will cause a

2,310,366 rotation of the screw shaft 44' and thus a linear movement of the yoke 3S'. As the yoke moves upward along the guide plate 33', the back of the chair will be moving simultaneously upward and outward, and, as the yoke moves downwardly along the guide plate, there is a simultaneous downward and inward movement of the seat. The uppermost position is shown by the broken line in Fig. 5. These changes in the position of the back of the chair relative to the seat effect simultaneously an increase in the back height and the seat length and simultaneously a decrease in the back height and the seat length.

This latter embodiment may also be provided with a locking means substantially similar to that described above. Such a means is illustrated in Figure 6, and the reference numbers correspond to the above description except that the stem 68' threadingly engages the yoke 36' and abuts the extended portion of the limb 68'.

It will be seen that, if the screw shaft 44' and its associated parts become broken or damaged, they may be removed without destroying the usefulness of the adjusting means, since the proper adjustment of back height and seat length may be made by sliding the back along the guide plate and then, when the desired position is obtained, the handle 67' may be turned in order to lock the back in that position.

Other embodiments of this invention may be constructed by those skilled in the art without deviating from the spirit of this invention. Such modifications are intended to come within the scope of the following claims to an extent commensurate with the art.