Magnetic Sensor HMD Power Down Circuit
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Solution Overview
Problem
Head-mounted displays (HMDs) experience unnecessary power consumption due to proximity sensors detecting storage cases or straps, leading to false activation and energy waste when not in use.
Innovation Solution
Incorporating magnetic sensors that detect a magnet in storage cases or straps to determine when the HMD is not in use, triggering a power-down mode via a circuit coupled to the sensors, utilizing Hall Effect, fluxgate magnetometer, or magnetoresistance sensors to produce sensor signals indicating storage mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a proximity sensor is used to detect when the user has put on or taken off the HMD, then the electronic display panel can be automatically turned on or off to conserve energy, but the proximity sensor may falsely detect objects such as storage cases or straps, causing unnecessary power consumption
Solution Approach 1:
A magnet is introduced as an intermediary element embedded in the storage case or strap, which serves as a unique identifier for storage mode. The magnetic sensor detects this specific magnet to distinguish storage scenarios from normal usage, preventing false activation while maintaining automatic power management functionality
Solution Approach 2:
The system changes the detection parameter from general proximity detection (which detects any object) to specific magnetic field detection (which detects only the magnet). This parameter change allows the system to differentiate between storage cases/straps containing a magnet and other objects, resolving the false detection issue while maintaining energy conservation
2Loss of energy
If a magnetic sensor is added to detect the magnet in storage cases or straps, then false activation can be prevented and power consumption reduced, but the device complexity increases
Solution Approach 1:
The patent replaces the proximity sensor's optical or capacitive detection mechanism with a magnetic field-based detection system. This substitution allows for more selective and reliable detection of storage mode through magnet presence, reducing false activations while the added complexity is offset by the simplicity of the magnet embedding approach
3Ease of operation
If the electronic display panel remains on to ensure it is always ready for use, then user convenience is improved, but energy is wasted when the HMD is in storage
Solution Approach 1:
The magnetic sensor continuously monitors for the presence of the magnet in storage cases or straps, enabling the system to detect storage mode in advance and automatically power down components before the user would need to use the device. This preliminary detection allows the HMD to be ready for use when needed while conserving energy during storage periods
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
Effectively reduces power consumption and prevents unnecessary activation by accurately distinguishing between usage and storage scenarios, thereby conserving energy and extending battery life.
Implementation Method 1
The magnetic sensor is a Hall Effect sensor, a fluxgate magnetometer, or a magnetoresistance sensor
Implementation Method 2
The magnetic sensor is a Hall Effect sensor, a fluxgate magnetometer, or a magnetoresistance sensor
Data Source
AI summary
A head mounted display (HMD) includes a magnetic sensor to produce a sensor signal responsive to detecting a magnet within a first threshold distance. The HMD also includes a circuit operatively coupled to the magnetic sensor. The circuit determines that the HMD is to be placed in a storage mode responsive to receiving the sensor signal from the magnetic sensor. The circuit powers down components of the HMD responsive to determining that the HMD is to be placed in the storage mode.