RELATE APPLICATIONS This application is a continuation of application Ser. No. 11/350,994, filed Feb. 9, 2006, now abandoned, the entire disclosure of which is incorporated herein by reference.
FIELD OF INVENTION This invention relates to an armrest support for the arms of a person seated in a chair, and more particularly to an armrest which is infinitely adjustable within the parameters of its movement to support the arm of a seated person regardless of the person's size and body geometry.
BACKGROUND OF THE INVENTION Armrests on chairs are usually fixed in one position. Some chairs have adjustable arms which are limited in their range of motion. Conventional movable armrests lock at specific default positions provided by the manufacturer. Adjustable armrests typically have a shaft with a sleeve for adjustable vertical movement, and/or have an adjustable angle using a pivot attached to the armrest.
Inasmuch as the geometry and comfortable positions of every human being is slightly different from that of other human beings, the ideal armrest would be one which is totally and infinitely adjustable in all three dimensions to accommodate the sitter no matter what his or her geometry. Also, the actual portion of the armrest that comes into contact with the sitter's arm should minimize pressure on the sitter's arm so as not to impede circulation or cause nerve pressure. In order to accomplish these ends, the armrest must be lockable in whatever position the sitter requires to be comfortable.
SUMMARY OF THE INVENTION Problems with the prior art are solved by the present invention, which provides an adjustable armrest device that supports the sitter's arm. The portion of the armrest that comes into contact with the person's arm is preferably of thick, soft, foamed plastic which is large enough to distribute the weight of a person's arm over a relatively large area, thereby causing little or no point pressure. The device to which the foamed plastic is attached is preferably made of steel or other metal, or high density plastic. The armrest structure is adjustable angularly in the anterior-posterior plane and also adjustable vertically. The arm structure is fixed to the chair and has a locking mechanism to hold the contacting portion of the armrest wherever the sitter desires. The arm structure can utilize a triangular arrangement rigid within the plane of the armrest when locked.
DESCRIPTION OF THE DRAWINGS FIG. 1 is a side view of an adjustable, lockable arm rest.
FIG. 2 is a front view of an assembled adjustable, lockable arm rest, and
FIG. 3 is a bottom view of an arm on which the armrest is supported.
FIG. 4 is a front view of a friction disk, the rear view being identical, and
FIG. 5 is a cross section thereof.
FIG. 6 is a side view of a locking shaft and cam assembly.
FIG. 7 is a plan view of a bracket with a 90 degree slot, FIG. 8 is a plan view of a bracket with a 180 degree slot, and FIG. 9 is a side view of the bracket of FIG. 7 and FIG. 8.
FIG. 10 is a side view of an alternate structure of the arm using a strut.
FIG. 11 is a front view of an embodiment of a bracket and locking shaft and cam assembly.
FIGS. 12A and 12B are side and plan views of another embodiment of the friction disk.
FIGS. 13A and 13B are front and side views of an embodiment of the bracket.
BRIEF DESCRIPTION OF SPECIFIC EMBODIMENTS Referring initially to FIGS. 1 and 2, the present invention is directed to an armrest and armrest support of a chair that, in certain embodiments, utilizes the principle of the triangle for its strength and to achieve its function; that is, a structure having three segments attached at their ends to form a triangle. As can be seen, in the plane of the triangle the arm can be moved to infinite positions within its range of movement.
In FIG. 1, the arm 2 of the chair includes an armrest pad 1 on which the sitter rests his arm. (Although described with reference to an armrest, the present structure could be used for an adjustable foot rest as well.) The pad is preferably sized so that regardless of the angle at which the arm is disposed, the user will have an adequate surface on which the rest his arm. The arm includes an arm slot 7 running substantially down its length and having a bulbous portion at one end of the slot that is wider than the slot width. Swivel pin 5 extends from a bracket 3 having a generally planar face and which is attached to the main chair structure (not shown), such as to the seat 18. The swivel pin has a bulbous head and a shaft portion, the shaft portion being sufficiently small to fit and be moveable within the arm slot, and the bulbous head being sufficiently small to fit within the bulbous portion of the arm slot but sufficiently large to retain the arm on the swivel pin. The swivel pin is equidistant with the points forming the bracket slot 9 formed in the bracket. That is, the bracket slot is preferably an arcuate slot having as its origin the swivel pin. The bracket slot could also be linear, or have a different curvature, but the preferred embodiment is an arc centered on the swivel point. The arm 2 can be pivotally adjusted on the swivel pin through the extent of the bracket slot 9 and longitudinally adjusted through the longitudinal length the arm slot 7.
In FIG. 2, it is seen that the bracket has an angled cantilevered portion 3a which is attached to the main chair structure, angled with respect to the bracket portion 3 to which the arm is attached. Though not preferred, the end of the swivel pin can be threaded and a screwed closure applied, or the pin can otherwise be capped with a device allowing movement along the slot but being wider than the slot. Positioned between the arm and the bracket and disposed around the swivel pin is a washer 12.
In FIGS. 2 and 3, the base 14 of the arm pad 1 is of a hard material such as plywood, plastic, or metal, and is affixed to the horizontal portion of the arm 2a in which is a located an pad slot 2b. The pad may be moved laterally towards and away from the arm by moving the pad along the pad slot, and loosening and tightening using the pad fixation device 17, preferably a screw-like device extending through the slot and engaging the base of the pad.
Referring to FIGS. 2 and 4, another portion of the bracket is attached to the arm by a locking mechanism, which is preferably a locking cam, but can be a threaded screw-like device. In the preferred cam embodiment, a locking rod 13 extends through both the arm slot and the bracket slot. The locking rod can be threaded at one end and secured by a cap nut 4, with a washer 16 between the cap nut and the bracket. Disposed between the bracket and the arm is a friction disk, described below. On the opposite side of the arm is a cam having lever 11 having a free end and an opposite cam end engaging a washer 15 that abuts the arm. The cam end of the lever is pivotally attached to the locking rod; the lever is shown in the locked position wherein the cam applies force to the arm through the washer; when unlocked (lever rotated to the left in FIG. 6) the pressure is released, allowing the arm to be moved within the two slots. When the cam is unlocked the arm can be moved freely so that the sitter can adjust the angle and position of the arm to wherever desired, to get in a comfortable position to rest or read or eat or any other action one takes when sitting.
The friction disk is shown in FIGS. 4 and 5. Because the cam force may not be sufficient by itself to lock the arm if sufficient weight is applied to the arm (such as by someone sitting on the pad), this invention utilizes a friction disk. As shown in these figures, the friction disk 6 is like a washer having a bore through the center, and a flange 8 that extends orthogonally from both sides of the washer (as shown in FIG. 5). The friction disk, being disposed between the arm and the bracket, contacts both the arm and the bracket at the flange, providing significantly less contact area than would a simple washer, and hence a higher frictional force. Thus, the cam force is transmitted to a smaller area, providing an effective greater force per area to keep the arm locked. While the flange is shown as continuous for ease of manufacture, the flange can be discontinuous, or may only be provided as a plurality or multiplicity of raised portions on one or both sides of the friction disk, the idea being to minimize the contact area and so provide a greater frictional force for locking the arm. Likewise, although shown in a circular geometry, the friction washer could be rectilinear or another geometry. Although not preferred, the friction disk can be eliminated by providing raised portions adjacent each of the arm slot and bracket slot along substantially the length of each slot, whereby the arm and the bracket thus contact each other only where the raised portions meet, again providing a reduced contact surface and a higher frictional force. Alternatively, instead of a lever cam a screw-type knob can be provided, with the locking arm being threaded, to tighten the structure and provide the desired compressive force.
FIG. 7 depicts the bracket as shown in FIGS. 1 and 2 with a slot extending 90 degrees. FIG. 8 depicts a bracket having a slot that extends 180 degrees. FIG. 9 is a side view of either FIG. 7 or FIG. 8 for the preferred embodiment wherein the bracket is cantilevered from the underside of the seat. Of course, a slot of any length can be used depending on the desired range of movement for adjusting the arm.
In operation, the user of the chair unlocks the lever, adjusts the height and orientation of the arm along the arm slot and the bracket slot, and locks the cam with the lever, fixing the arm position. An advantage of the two slots and in combination with the locking cam is that the user need not rely on fixed serial adjustment points as provided in existing armrests, which provide digital set points, but can adjust the arm infinitely (analog) in any desired position within the available range of movement allowed by the slots.
In another embodiment, shown in FIG. 10, the seat 18 is seen in side view (alternatively, 18 can be a bracket attached to the chair or seat). Affixed to the seat is a strut pivot 17 attached to fixation strut 22 having a strut slot 20 running substantially its length. Also affixed to the seat 18 is the a swivel pin 19 that extends through arm slot 21 in arm 23 and has a bulbous end like swivel pin 5. Where the arm 23 and the strut 22 cross is a locking rod 13 similar to the rod of locking mechanism in FIGS. 1, 2, and 4, and the associated structure of the lever and friction disk disposed between the arm and the strut. This rod goes through the slots 20 and 21, thereby pivotally connecting them. As described above, when the desired position is achieved, the lever cam 11 is locked. The pins 17 and 19 form the fixed side of a triangle, and when the lever is locked the other two legs of the triangle become fixed, thereby locking the arm and strut orientation to the chair and providing a locked and secured structure.
In another embodiment, as shown in FIG. 11, the locking force of the friction disk can be directed to opposing sides of the arm. An annular friction disk 101 having a single face with a flange 102 is disposed on shaft 107. One end of the shaft provides connection to a lever 108 at pivot 109, the lever including a cam portion 112. that acts on the disk face opposite from the face having the flange. The cam portion of the lever is preferably U-shaped. Bracket 103 having a bottom portion 103a has an orifice though which the other end of the rod projects and is secured by cap 110, with a washer 111 between the cap and the inside (side facing the person seated) of the flange. Attached to the outside of the bracket is a friction portion 113 having a flange 115. The mechanism is disposed about the arm, as described above, with the cam lever compressing the flanges 102 and 115 against opposite sides of the arm.
In an especially preferred embodiment, the arrangement shown in FIG. 11 includes a square bore in the friction disk, the friction portion, or both. As seen in FIGS. 12A and 12B, side and plan views, respectively, of a friction disk suitable for use in the apparatus of FIG. 11, the bore 121 can be non-round; a square embodiment is shown. Of course, the portion of the locking shaft passing through should also be square. Although a square embodiment has been shown, the bore could be triangular, rectangular, or any regularly shaped polygon, or an irregularly shaped polygon, or oval, or hemispherical. In essence, by “non-round” is meant a geometry between the bore and the rod that does not allow rotation between the disk and the rod. The non-rotating arrangement can also be used on the bracket, as shown in FIGS. 13A and 13B, side and front views, respectively, of the bracket attached to the chair 118.
FIG. 14 is another embodiment where the arm does not have a slot (the camming clamp mechanism is not shown). In this case the arm 1401 is a solid piece having one or more extensions 1403 on which the arm rest 1405 is supported.
While the foregoing has been described with respect to a chair, it is evident that this invention can find use in fixed seating devices, such as seats on planes, buses, cars, and other vehicles, or in movie theaters, or on wheelchairs. While armrests are typically provided on seating devices, the armrests could instead be attached to a structure such as a workbench, desk, table, or podium. The armrest is most preferably used with the chair as described in U.S. Pat. No. 6,244,659, the disclosure of which is incorporated herein by reference.
The foregoing description is meant to be illustrative and not limiting. Various changes, modifications, and additions may become apparent to the skilled artisan upon a perusal of this specification, and such are meant to be within the scope and spirit of the invention as defined by the claims.
