Swing Input Knob Magnetic Shielding for Detection Accuracy
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Solution Overview
Problem
Existing swing type input apparatuses using magnetic sensors for detecting the angle of rotation of an operation knob face challenges in achieving high detection accuracy due to misalignment between the magnet and the operation knob, and are susceptible to static electricity and external magnetic fields, leading to unreliable signal detection.
Innovation Solution
The apparatus includes a housing with a magnetic sensor and magnet positioned to intersect the rotation center line of the operation knob, covered by a magnetic shield case with a grounding tab to prevent external interference and ensure accurate detection, reducing the difference in rotation between the knob and magnet, and using a magnetic shield case to prevent erroneous detection by external magnetic fields and static electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnet is placed near the magnetic sensor to increase detection accuracy, then the detection accuracy is improved, but the apparatus becomes susceptible to static electricity and external magnetic fields
Solution Approach 1:
A magnetic shield case made of magnetically permeable material is introduced as an intermediary between the magnet/magnetic sensor and the external environment. This shield case attracts and redirects external magnetic field lines away from the detection components, while static electricity is directed to a grounding tab for safe discharge, thereby protecting the sensitive detection system without requiring increased detection sensitivity
Solution Approach 2:
The harmful factors (external magnetic fields and static electricity) are extracted and separated from the detection system by providing dedicated pathways: the magnetic shield case extracts and redirects magnetic field interference, while the grounding tab extracts and directs static electricity to ground, allowing the magnet and magnetic sensor to operate in a protected environment
2Object-affected harmful factors
If the magnet is positioned away from the rotation center line to avoid interference, then susceptibility to interference is reduced, but detection accuracy deteriorates due to rotation difference between the operation knob and magnet
Solution Approach 1:
The magnetic shield case acts as a protective intermediary that allows the magnet to be positioned optimally near the rotation center line for high detection accuracy, while simultaneously blocking external magnetic field interference from reaching the detection components
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 configuration enhances detection accuracy and reliability by minimizing the impact of external magnetic fields and static electricity, allowing for precise angle detection of the operation knob, effectively increasing the apparatus's susceptibility to interference.
Implementation Method 1
a magnetic sensor attached to the circuit substrate, a magnet holder driven by the operation knob such that the magnet holder is rotated integrally with the operation knob, a magnet held by the magnet holder
Implementation Method 2
a magnetic shield case fixed to the circuit substrate so as to cover at least both of the magnetic sensor and the magnet
Data Source
AI summary
A swing type input apparatus includes a housing, an operation knob rotatably supported by the housing, and a detecting unit detecting an angle of rotation of the knob. The detecting unit includes a circuit substrate intersecting the rotation center line of the knob, a magnetic sensor on an extension of the circuit substrate, a magnet holder driven by and rotated with the knob, a magnet held by the magnet holder such that the magnet intersects the rotation center line and is close to and faces the magnetic sensor, and a magnetic shield case which covers the magnet and the magnetic sensor and is a boxy assembly of first and second shield cases. The boundary between the first and second shield cases is positioned so as not to overlap the magnet. A bent grounding tab in the second shield case is electrically connected to a grounding conductor of a sub substrate.