# US 2016/0256342 A1 · Armrest assembly and stool for dental practitioner > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0256342 A1 - Document ID: US20160256342A1 - Status: Published application - Kind: A1 - Application number: 14/639,944 - Filed: 2015-03-05 - Published: 2016-09-08 - Earliest claimed: 2015-03-05 - Assignees: A-dec, Inc. - Applicants: A-dec, Inc. - Inventors: Jason Alvarez; Timothy Klus, JR. - Web page: https://patentgrep.com/patent/US20160256342A1 ## CPC - A47C 1/0303: {adjustable rectilinearly in vertical direction} - A47C 1/03: the parts being arm-rests - A47C 1/0307: {adjustable rectilinearly in horizontal direction} - A47C 1/0308: {adjustable by rotation} - A47C 7/006: {with castors} - A47C 7/402: {adjustable in height} - A47C 7/48: of freely-rotatable type - A47C 7/506: {of adjustable type} - A47C 7/5066: {by rotation} - A47C 9/005: {with forwardly inclined seat, e.g. with a knee-support} - A47C: CHAIRS; SOFAS; BEDS ## Abstract An adjustable armrest assembly for a stool or chair comprises an armrest base, an armrest support member and an adjustment assembly. The armrest base is connectible to the stool or chair and has a first opening. The armrest support member has a first end with a second opening. The first end is positionable with the second opening aligned with the first opening. The armrest support member has a second end opposite the first end and extending distally to support an armrest. An adjustment assembly is positionable to extend through the second opening and the first opening to define a pivot axis and an adjustable pivot connection between the support member and the base. The assembly is movable within at least one of the first opening and the second opening to laterally reposition the pivot axis. A variable friction member applies a selected degree of resistance to the adjustable pivot connection. ## Claims ### Claim 1 An adjustable armrest assembly for a stool or chair, comprising: an armrest base connectible to the stool or chair and having a first opening; an armrest support member having a first end with a second opening, the first end being positionable with the second opening aligned with the first opening in the armrest base, the armrest support member having a second end opposite the first end and extending distally to support an armrest; an adjustment assembly positionable to extend through the second opening and the first opening to define a pivot axis and an adjustable pivot connection between the armrest support member and the armrest base, wherein the adjustment assembly is movable within at least one of the first opening and the second opening to laterally reposition the pivot axis, and the adjustment assembly has a variable friction member that applies a selected degree of resistance to the adjustable pivot connection. ### Claim 2 (depends on 1) The adjustable armrest assembly of claim 1, wherein the adjustment assembly comprises a hand knob tightenable to position the axis of rotation. ### Claim 3 (depends on 1) The adjustable armrest assembly of claim 1, wherein the first opening in the armrest base is circular and wherein the second opening in the armrest support is slotted, and wherein the armrest support can be moved laterally relative to the armrest base while the slotted opening is aligned with the circular opening to reposition the pivot axis. ### Claim 4 (depends on 1) The adjustable armrest assembly of claim 1, wherein the armrest support member is adjustable to change a height of an armrest attached to the distal end. ### Claim 5 (depends on 1) The adjustable armrest assembly of claim 1, wherein the variable friction member comprises a threaded member and a nut. ### Claim 6 (depends on 1) The adjustable armrest assembly of claim 1, wherein the adjustment assembly comprises a threaded extension with a hand knob, the threaded extension being positioned to extend along the pivot axis, and wherein the variable friction member comprises a threaded member positioned to extend in the axial direction and tightenable to exert an axial force on the threaded extension. ### Claim 7 (depends on 6) The adjustable armrest assembly of claim 6, wherein the threaded extension is configured to extend through the first and second openings and be received in a pivot hub positioned on a lower side of the armrest support, and wherein the variable friction member comprises a friction adjustment screw positionable to bear against the pivot hub. ### Claim 8 (depends on 7) The adjustable armrest assembly of claim 7, further comprising a friction isolation bearing positioned between the friction adjustment screw and the pivot hub. ### Claim 9 (depends on 7) The adjustable armrest assembly of claim 7, further comprising a backer plate configured for attachment to the armrest support to hold the friction adjustment screw in place. ### Claim 10 (depends on 9) The adjustable armrest assembly of claim 9, wherein the backer plate comprises apertures for fasteners to attach the backer plate to a lower surface of the armrest support. ### Claim 11 (depends on 6) The adjustable armrest assembly of claim 6, further comprising a nut, wherein the threaded member comprises an exposed end sized to receive the nut, and the nut can be tightened or loosened relative to the exposed end to vary the friction applied to the pivot connection. ### Claim 12 (depends on 6) The adjustable armrest assembly of claim 6, her comprising at least one thrust bearing positioned around the threaded extension. ### Claim 13 (depends on 6) The adjustable armrest assembly of claim 6, further comprising at least one thrust washer positioned around the threaded extension. ### Claim 14 (depends on 6) The adjustable armrest assembly of claim 6, further comprising at least one low friction washer positioned around the threaded extension. ### Claim 15 (depends on 8) The adjustable armrest assembly of claim 8, wherein the friction isolation bearing comprises a thrust bearing, a first thrust washer on a first side of the thrust bearing and a second thrust washer on a second side of the thrust bearing opposite the first side. ### Claim 16 (depends on 1) The adjustable armrest assembly of claim 1, wherein the armrest support comprises a mounting section and yoke connectible to the mounting section to mount the armrest support to a shaft of a chair or stool. ### Claim 17 A stool for dentistry, comprising: a leg assembly with multiple feet; a seat assembly supported by the leg assembly, the seat assembly comprising a seat, a seat back support assembly extending from a rear area of the seat and a seat back coupled to the seat back support; an armrest base connectible to the leg assembly at a height below the seat, the armrest base having at least one first opening; at least one armrest support member having a first end with a second opening, the first end being positionable with the second opening aligned with the first opening in the armrest base, the armrest support member having a second end opposite the first end and extending distally; an armrest connectible to the distal end of the armrest support; and an variable friction adjustment assembly positionable to extend through the second opening and the first opening to define a pivot axis and an adjustable pivot connection between the armrest support member and the armrest base, wherein the adjustment assembly is movable within at least one of the first opening and the second opening to laterally reposition the pivot axis. ### Claim 18 (depends on 17) The stool of claim 17, wherein the seat back support is tilt adjustable. ### Claim 19 (depends on 17) The stool of claim 17, wherein the seat back support is height adjustable. ### Claim 20 (depends on 17) The stool of claim 17, wherein the at least one armrest support member and variable friction adjustment assembly are positioned on a right side, and the armrest is a right armrest, further comprising a left armrest support assembly, left variable friction adjustment assembly and left armrest, and wherein the left armrest and the right armrest are each pivotable independently of each other and through a range of positions.