Motion Sensor Using Rotating Bipolar Magnets
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Solution Overview
Problem
Existing motion sensors for detecting rotational motion, such as in electric shavers, are costly and prone to failure due to the need for complex mechanical designs and components like sense ring magnets, which increase size limitations and complexity.
Innovation Solution
A motion sensor system utilizing a rotating member with affixed bipolar magnets and a transducer, such as a Hall effect sensor, to detect changes in the magnetic field, allowing for accurate determination of angular rotation and motion parameters like velocity and direction without the need for costly components like sense ring magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a belt is used to translate motion of the roller to the generator, then motion can be detected, but the system becomes cumbersome and prone to failure due to clogging
Solution Approach 1:
The patent combines the generator and magnetometer into a single integrated unit that rotates with the roller, eliminating the need for a separate belt mechanism. This merging of components reduces mechanical complexity and eliminates belt-related failure modes while maintaining reliable motion detection through direct magnetic field sensing.
2Device complexity
If the generator is integrated within the roller, then complexity is reduced, but electrical connections to a rotating body are required which increases cost
Solution Approach 1:
The patent replaces the mechanical belt-driven generator system with a magnetic field-based magnetometer that directly senses roller rotation. This substitution eliminates the need for electrical connections to rotating components, reducing manufacturing complexity and cost while maintaining accurate motion detection capability.
3Measurement precision
If a sense ring magnet is used for detecting rotational speed, then detection accuracy is improved, but cost increases and size limitations are imposed
Solution Approach 1:
The patent extracts the magnet from the traditional sense ring configuration and positions it on the roller surface where it directly interacts with the magnetometer. This extraction simplifies the overall structure by eliminating the need for a separate sense ring assembly, reducing component count and complexity while maintaining accurate rotational speed detection through direct magnetic field measurement.
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
This solution reduces costs and complexity while providing reliable detection of rotational motion, suitable for aesthetic and medical treatment devices, by using bipolar magnets and Hall effect sensors to determine motion parameters effectively.
Implementation Method 1
A transducer is further provided arranged to vary its output voltage in response to changes in magnetic field, the transducer juxtaposed with the rotating member so as to detect changes in the magnetic field from the rotation of the one or more bipolar magnets. In one embodiment, the transducer is a Hall effect sensor.
Data Source
AI summary
A motion sensor constituted of: a housing; a rotating member secured to the housing and arranged to rotate about a rotation axis of the rotating member responsive to motion of the housing across a surface; at least one bipolar magnet secured to the rotating member so as to rotate about the rotation axis of the rotating member with the rotation of the rotating member; and a transducer secured to the housing and juxtaposed with the rotating member, the transducer arranged to vary its output voltage in response to changes in magnetic field caused by the rotation of the at least one bipolar magnet.