Electric Shaver Head Asymmetrical Link Mechanism
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Solution Overview
Problem
Conventional electric shavers experience uneven shaving performance due to varying reactive forces from biasing mechanisms, leading to inconsistent swing characteristics, especially on uneven shaving areas, and require a more compact design to improve following performance.
Innovation Solution
An electric shaver with a head part swingably attached via a link mechanism featuring asymmetrical link arms and connecting axes, allowing for optimal positioning of swing axes and moment arms to enhance torque and stability, thereby improving shaving performance on uneven surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a biasing mechanism such as a coil spring is attached to generate reactive force against swing, then the head part can be brought back to its original position, but the reactive force varies among swing directions leading to inconsistent swing characteristics
Solution Approach 1:
The patent applies asymmetry by configuring the link arms with different lengths (first link arm longer than second link arm) and positioning the swing axis asymmetrically relative to the head part's center of gravity. This asymmetric configuration ensures that the gravitational force and link mechanism provide consistent reactive force in both clockwise and counterclockwise swing directions, eliminating the variability problem caused by symmetric biasing mechanisms.
2Adaptability or versatility
If the head part is made to swing freely to improve following performance on uneven areas, then shaving performance improves, but the device size increases due to swing mechanism requirements
Solution Approach 1:
The patent segments the support structure into multiple link arms (first and second link arms) connected at a swing axis, allowing the head part to swing independently while keeping the body part compact. This segmentation enables the swing function to be achieved without increasing the overall device volume, as the link arms are integrated into the existing structure.
Solution Approach 2:
The patent introduces a swing dimension by allowing the head part to rotate about a swing axis that is separate from the longitudinal axis. This adds a rotational degree of freedom in another dimension, enabling the head part to adapt to uneven surfaces while maintaining a compact linear device form factor.
3Adaptability or versatility
If the swing axis position is optimized for better following performance, then consistent shaving across different directions is achieved, but the device complexity increases
Solution Approach 1:
The patent applies local quality by specifically positioning the swing axis and configuring the link arms with different lengths to create asymmetric local geometry. This localized asymmetric configuration at the link mechanism provides consistent reactive force in all swing directions, achieving shaving consistency without requiring complex overall device redesign.
Data Source
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AI summary
An electric shaver (1) includes a rod-shaped body part (2), a head part (3) , and a link mechanism (9). The head part projects from one end portion (2a), in a longitudinal direction, of the body part and is swingably attached to the body part with a support base (8,9a) between the body part and the head part. The head part includes a shaving portion (4) and a drive mechanism (5). The shaving portion is formed to be elongated in a direction orthogonal to a projecting direction of the head part and has paired blades (4a,4b) configured to operate relative to each other. The drive mechanism is configured to drive at least one of the paired blades. The link mechanism includes two link arms (9b) each connected to the support base and the head part respectively at connecting axes parallel to a longitudinal direction of the shaving portion. The link mechanism is configured to support the head part on the support base swingably. The two link arms are disposed asymmetrically with respect to a straight line (G) passing on a center of gravity of the head part and extending parallel with the projecting direction of the head part, when viewed in the longitudinal direction of the shaving portion.