Sonic Toothbrush Brush Geometry for 2D Bristle Motion
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Solution Overview
Problem
Existing sonic toothbrushes lack a defined and controlled two-dimensional movement of bristles, leading to inefficient cleaning and potential damage to gums, while existing technologies fail to optimize the cleaning effect and comfort simultaneously.
Innovation Solution
A sonic toothbrush with a brush design featuring a frustoconical base portion, a head portion with bristle support, and a neck portion with a tapered cross-section, incorporating a kink angle and geometric alignment to create a two-dimensional '8' movement of the bristles, enhancing interdental cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If the brush head is moved far from the pendulum axis to increase movement intensity, then the movement intensity is homogeneously distributed over the bristle field, but relatively large forces (moments) occur because the brush head with its mass is relatively far away from the pendulum axis
Solution Approach 1:
The patent transitions from a traditional pendulum oscillation (one-dimensional arc motion) to a rotation-fixed coupling mechanism where the brush head rotates around the longitudinal axis of the toothbrush drive. This dimensional change allows the bristles to move in a circular pattern while maintaining a fixed distance from the rotation axis, achieving homogeneous movement distribution without increasing the moment arm and thus avoiding excessive forces on gums.
Solution Approach 2:
The patent replicates the beneficial circular movement pattern of manual toothbrushes through the rotation-fixed coupling mechanism. The bristles follow a circular trajectory similar to manual brushing motions, creating gentle and efficient cleaning action without the need for large oscillation amplitudes that would generate harmful forces.
2Weight of moving object
If round brush head rotates back and forth to achieve small moving part size, then the moving part is very small and does not need much drive energy, but the bristle movement depends on the distance from the axis of rotation resulting in very inhomogeneously distributed movement
Solution Approach 1:
The patent changes the motion dimension from radial oscillation (where bristle movement varies with distance from axis) to axial rotation (where all bristles move together in a circular pattern). This ensures that every bristle in the field experiences the same movement amplitude regardless of its position, achieving homogeneous movement distribution while keeping the brush head compact and energy consumption low.
3Device complexity
If housing vibration is used to simplify motion transmission, then one does not have to deal with the technical details of the motion transmission, but one has to vibrate the entire housing requiring more drive energy and the effective movements of the bristles are not known
Solution Approach 1:
The patent extracts the vibration generation function from the entire housing and concentrates it in a small, dedicated drive mechanism (rotation-fixed coupling) located at the brush neck. Only the necessary components (drive adapter, brush neck, and bristle field) are vibrated, not the entire housing. This reduces drive energy consumption while maintaining simple motion transmission and providing defined, controllable bristle movements.
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
The design achieves a gentle and effective two-dimensional bristle movement, optimizing cleaning efficiency and reducing gum damage by forcing saliva and toothpaste into interdental spaces, while maintaining stable attachment and efficient vibration transmission.
Implementation Method 1
a sonic toothbrush drive with longitudinal axis vibration
Implementation Method 2
a frustoconical base portion... a neck portion with a tapered cross-section... incorporating a kink angle and geometric alignment to create a two-dimensional '8' movement of the bristles
Data Source
AI summary
A brush for a sonic toothbrush with longitudinal axis vibration having an elongated base body has a frustoconical base portion with a drive adapter for rotation-fixed coupling to a sonic toothbrush drive with longitudinal axis vibration, and a head portion with a bristle support in which a plurality of bristles are anchored, and an elongated neck portion connecting the base portion and the head portion is disclosed. The base body forms a kink angle in that a geometric base portion longitudinal axis and a geometric head portion alignment axis include an angle γ in the range of 5° to 12°. A geometric kink position in the base body has a distance from an end face of the base portion of at least 50% of a total length of the base body.