Headrest Linkage and Spring Geometry for Uniform Adjustment Force
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Solution Overview
Problem
Existing headrest moving devices require increased user force as the headrest is moved further from its initial position due to a fixed stopping position, leading to inconvenient operation.
Innovation Solution
A headrest moving device with a moving unit connected to a stay rod, a locking unit, and a return spring where the contact position between the moving unit and the return spring varies with the headrest's position, using a system of links and a ratchet mechanism to maintain consistent operational forces across different positions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the headrest is moved further from the initial position, then the headrest can be adjusted to a wider range of positions, but the force required to move the headrest increases significantly
Solution Approach 1:
The patent applies the dynamics principle by making the return spring's contact position variable rather than fixed. As the headrest moves to different positions, the contact position on the moving unit changes, which dynamically adjusts the spring's leverage arm length. This dynamic adjustment compensates for the increasing distance from the pivot point, maintaining relatively constant operational force across the full adjustable range while preserving wide adaptability.
2Device complexity
If a fixed stopping position is used for the headrest, then the locking mechanism is simple, but the operational force varies significantly at different positions
Solution Approach 1:
The patent implements dynamics by transitioning from a fixed stopping position to a variable contact position system. The moving unit's geometry is designed so that as the headrest moves along its trajectory, the contact point between the return spring and moving unit shifts position. This dynamic adjustment maintains consistent mechanical advantage throughout the range of motion, improving ease of operation without significantly complicating the locking mechanism.
3Device complexity
If the contact position between the moving unit and return spring is fixed, then the structure is simple, but the user must apply increasing force as the headrest moves further
Solution Approach 1:
The patent resolves this contradiction by implementing a dynamic contact position system. The moving unit is designed with specific geometric features that cause the contact position with the return spring to vary as the headrest moves. This variable contact position adjusts the spring's effective leverage arm, maintaining consistent operational force throughout the range of motion while adding only moderate structural complexity through carefully designed linkages and contact surfaces.
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
Enhances user convenience by maintaining consistent operational forces when moving the headrest to either its minimum or maximum position, simplifies the moving unit structure, and allows for a more compact design.
Implementation Method 1
a return spring, whose one portion is fixed to the stay rod and the other portion is in contact with the moving unit, for returning the moving unit
Implementation Method 2
The locking unit includes a ratchet and a pole which is geared with the ratchet
Implementation Method 3
a pole which is geared with the ratchet
Data Source
AI summary
The present invention relates to a headrest moving device, more particularly, relates to a headrest moving device wherein the user convenience is enhanced since the contact position between the moving unit and the return spring is changed according to the position of the headrest so that the forces being applied by a user are same or similar, that is, there is no significant difference in the operational forces when moving the headrest to either the minimum position or the maximum position thereof.