Pivotable Treatment Head Cam Spring Feedback Mechanism

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Solution Overview

Problem

Existing personal care devices lack an effective return force mechanism that provides feedback and ensures the treatment head returns to its rest position after pivoting, which affects the user experience and operational efficiency.

Innovation Solution

A personal care device with a treatment head that pivots around a swivel axis, utilizing a spring element and cam surface interaction, where the spring element biases the pin head against the cam surface, providing a biasing force that must be overcome to pivot the head, and the increasing spring force acts to return the head to its rest position, with the cam surface shape ensuring the spring force increases with pivot angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a spring element is used to provide return force for the pivoting treatment head, then the treatment head returns to its rest position, but the device complexity increases due to additional components

Engineering Contradiction:
Improvereturn to rest positionVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the return force function with the pivot joint structure itself. The spring element is integrated into the pivot joint assembly, and the cam surface is formed as part of the pivot joint components rather than as a separate mechanism. This merging reduces overall device complexity while maintaining the reliable return-to-rest-position function.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The treatment head automatically returns to its rest position through the spring element without requiring user intervention. The cam surface geometry automatically converts the pivoting motion into spring compression, and the spring's inherent elastic property provides the self-service return force, eliminating the need for additional control mechanisms.

Inventive Principle:
Principle #25Self-service

2Ease of operation

If a cam surface is shaped to increase spring force with pivot angle, then precise control and user feedback are improved, but manufacturing precision requirements increase

Engineering Contradiction:
Improveuser feedbackVSAvoidcam surface shape
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The cam surface is designed with specific geometric parameters that cause the spring force to increase progressively with pivot angle. By carefully selecting the cam surface curvature and profile parameters, the patent achieves smooth, progressive resistance that provides intuitive user feedback without requiring extreme manufacturing tolerances. The parameter optimization balances feedback quality with manufacturability.

Inventive Principle:
Principle #35Parameter changes

3Stability of the object's composition

If a spring element with biasing force is used, then the treatment head remains stable at rest position, but more force is required to pivot the head

Engineering Contradiction:
Improvestability at rest positionVSAvoidforce to pivot
Core Design Contradiction:
Stability of the object's compositionVSForce

Solution Approach 1:

The patent creates a dynamic balance where the spring biasing force provides stability at rest but allows controlled movement when force is applied. The cam surface geometry dynamically adjusts the mechanical advantage during pivoting, making the system stable at rest position while enabling smooth transition when the user applies force. The force requirement is optimized to provide both stability and operability.

Inventive Principle:
Principle #15Dynamics

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 solution provides a clear feedback to the user by requiring a force to be overcome before pivoting, ensures precise control, and effectively returns the treatment head to its rest position, enhancing user experience and operational efficiency.

Implementation Method 1

a spring element and a cam surface (151, 1661), where the spring element biases the pin head (166) against the cam surface (151, 1661)

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP3663058B1Personal care device with pivotable treatment head
Publication Date: 2023.05.03 BRAUN GMBH
  • EP3663058B1 patent drawingFigure 1
  • EP3663058B1 patent drawingFigure 2
  • EP3663058B1 patent drawingFigure 3A~3B

AI summary

The present disclosure is concerned with a personal care device with a treatment head being pivot-mounted around a pivot axis with respect to a body of the personal care device, the personal care device having a pin having a pin head, the pin being provided at one of the treatment head or body, a cam element having a cam surface being provided at the other one of the treatment head or body, a spring element biasing the pin head and the cam surface against each other, wherein the pin head is in contact with the cam surface and the cam surface is shaped such that it defines a rest position at which the biasing spring force provided by the spring element with which the pin head and the cam surface are pushed against each other has a non-zero minimum value, and wherein a pivoting of the head around the pivot axis causes the pin head to move along the cam surface and the cam surface is further shaped such that the spring force pushing the pin head and the cam surface against each other increases with increasing pivoting angle.