J-Back Chair Adjustment Mechanism Using Opposed Wedges
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing office chair mechanisms do not allow for adjustable angles of the J-back support bar, limiting user comfort and adaptability.
Innovation Solution
A J-back adjustment mechanism using two opposed wedges to vertically move the end portion of the J-back support bar about a pivot point, allowing the angle of the back to be changed through a range of motion via a tilt wedge, slide wedge, adjusting shaft, and knob system.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the J-back support bar angle is made adjustable, then user comfort and adaptability are improved, but device complexity increases
Solution Approach 1:
The adjustment mechanism is divided into separate functional components: a tilt wedge for angular adjustment, a slide wedge for vertical movement, a threaded shaft for controlled displacement, and a knob for user operation. Each component performs a specific function in the adjustment sequence, making the overall system manageable despite its complexity.
Solution Approach 2:
The mechanism transforms the static J-back support bar into a dynamically adjustable component. The tilt wedge enables the support bar to change its angle dynamically, while the slide wedge provides vertical positioning. This dynamic capability allows the backrest to adapt to different user preferences and positions.
2Adaptability or versatility
If the J-back support bar angle is made adjustable through multiple wedges and shafts, then range of motion is improved, but ease of manufacture deteriorates
Solution Approach 1:
Multiple adjustment functions are merged into a compact assembly housed within a single casing. The tilt wedge, slide wedge, threaded shaft, and knob are integrated into one unified mechanism that operates through a single user interface (the knob), simplifying both manufacturing and assembly compared to separate adjustment systems.
Solution Approach 2:
The mechanism employs a nested arrangement where the slide wedge is positioned within the tilt wedge structure, and the threaded shaft is housed within the slide wedge. This nesting consolidates multiple moving parts into a compact package, reducing the overall space required and simplifying the manufacturing process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables adjustable angles of the J-back support bar, enhancing user comfort and adaptability by allowing the back to change its angle with respect to the chair seat, applicable to existing mechanisms without prior adjustability.
Implementation Method 1
The slide wedge contains a plurality of sliding surfaces that are angled and designed to mate with the angled surfaces of the tilt wedge
Implementation Method 2
the slide wedge includes a shaft receiving threaded bore. This bore couples the slide wedge to the adjusting shaft
Data Source
AI summary
An adjustment mechanism for use with a chair. The adjustment mechanism is for use on a chair that has a base assembly with an extending pedestal, a seat, a chassis, and a back. Specifically the adjustment mechanism is for use on a chair that utilizes a J-back bar that couples the chassis to the back. The J-back adjustment mechanism allows the angle of the J-back bar and thus, the back to be changed throughout a range of motion. The J-back adjustment assembly includes a casing and an adjustment portion, wherein rotation of the adjustment portion changes the inclination of the J-back bar and, thus, the back with respect to the seat.