Magnetic Sensor Shunt Layout for Multi-Accessory Cover Detection
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Solution Overview
Problem
Electronic devices face limitations in detecting magnets in accessory devices due to proximity issues, leading to false triggers and compatibility challenges, and there is a need to prevent unwanted detection of internal magnets while allowing detection of external magnets for accessory compatibility.
Innovation Solution
Incorporating a shunt assembly that alters or redirects magnetic fields from internal magnets to prevent detection by the magnetic field sensor, while allowing detection of external magnets, and using a switching circuit to deactivate the microphone based on magnetic field sensor inputs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the magnetic field sensor is placed in proximity to internal magnets to detect accessory magnets, then the detection sensitivity is improved, but false triggers occur due to detection of internal magnets
Solution Approach 1:
A shunt assembly is introduced as an intermediary component between the internal magnets and the magnetic field sensor. The shunt assembly selectively redirects magnetic flux to allow detection of external accessory magnets while blocking or reducing the magnetic field from internal magnets, thereby resolving the contradiction between detection sensitivity and false trigger prevention
Solution Approach 2:
The magnetic field environment is differentiated into distinct zones: one allowing external magnetic field penetration to the sensor, and another where internal magnetic fields are redirected or shielded by the shunt assembly. This creates local variations in magnetic permeability and flux distribution to achieve selective detection
2Adaptability or versatility
If multiple sensors are added to detect various accessory devices, then accessory compatibility is improved, but device complexity increases
Solution Approach 1:
A single magnetic field sensor is designed to perform multiple detection functions by strategically positioning it and using a shunt assembly to redirect magnetic flux from different internal magnets. This allows one sensor to detect multiple types of accessory devices that would otherwise require multiple sensors, reducing overall system complexity while maintaining broad compatibility
3Reliability
If the magnetic field sensor is positioned away from internal magnets to avoid false triggers, then false trigger rate is reduced, but detection capability for external magnets is weakened
Solution Approach 1:
The shunt assembly serves as a magnetic flux mediator that is positioned between internal magnets and the sensor. It allows the sensor to be placed in a location that is naturally shielded from internal magnetic fields while the shunt assembly actively redirects external magnetic flux toward the sensor, thus improving both reliability and detection capability simultaneously
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
Enables compatible detection of magnets in various accessory devices without false triggers, enhances user privacy by disabling the microphone when an accessory covers the display, and improves the signal-to-noise ratio for accurate magnetic field detection.
Implementation Method 1
a shunt assembly that alters the first magnetic field below the threshold magnetic field at the magnetic field sensor
Implementation Method 2
the magnetic field sensor provides the switching signal based upon detection of a second magnetic field from a magnet external to the enclosure and the display assembly
Data Source
AI summary
An electronic device is disclosed. The electronic device includes a device magnet designed to magnetically couple with an accessory device magnet. The electronic device further includes a display assembly and a magnetic field sensor configured to detect the accessory device magnet, thereby providing an indication that the accessory device is covering the display assembly. The electronic device further includes a shunt assembly designed to reduce the magnitude of the magnetic field of the device magnet, as determined by the magnetic field sensor, while allowing the magnetic field from the accessory device to sufficiently reach the magnetic field sensor. As such, the magnetic field sensor can be placed near the device magnet without triggering the magnetic field sensor. The electronic device may further include a microphone. Communication between the microphone and an integrated circuit can cease based on the magnetic field sensor detecting the accessory device magnet.