HMD Wireless Power Management for Continuous Wearable Use
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Solution Overview
Problem
Conventional non-contact power transfer methods for wearable devices, such as head-mounted displays (HMDs), are inadequate for continuous use due to limited battery capacity, weight concerns, and the inconvenience of cable connections, which disrupt user experience and increase the risk of terminal corrosion from sweat.
Innovation Solution
A wearable device with multiple wireless power receivers and a power supply manager that switches between batteries, preventing reverse current and displaying low power warnings, allowing continuous use without cable connections and reducing weight by distributing power across multiple batteries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If the capacity of the onboard battery is increased to enable continuous use of the HMD while being worn, then the usable time is improved, but the weight increases which adversely affects the feeling of wearing
Solution Approach 1:
The power supply system is segmented into multiple independent batteries (first battery and second battery) that can be used alternately. This allows the HMD to switch between batteries when one is depleted, effectively extending the total usable time without requiring a single large-capacity battery that would increase weight.
2Use of energy by moving object
If the HMD is connected to an external power supply with a cable for charging during use, then the power supply is improved, but the user experience deteriorates due to troublesomeness of cable connection
Solution Approach 1:
The mechanical cable connection system is replaced with a wireless power transmission system using electromagnetic induction. The HMD includes a power receiving coil that wirelessly receives power from an external power transmission coil, eliminating the need for physical cable connections while maintaining continuous power supply capability.
3Use of energy by moving object
If the HMD is connected to an external power supply with a cable, then the power supply is improved, but the risk of terminal corrosion from sweat increases
Solution Approach 1:
The cable connection with exposed terminals is replaced by a wireless power transmission system. The power receiving coil is embedded within the HMD structure without exposed external terminals, eliminating the corrosion risk from sweat while maintaining power supply capability.
4Duration of action of moving object
If multiple batteries are used to extend usable time, then the duration of action is improved, but the device complexity increases
Solution Approach 1:
The power supply manager automatically monitors the charge levels of multiple batteries and performs switching operations without user intervention. The system self-manages the complexity of multiple battery operations, presenting a simple interface to the user while extending usable time through automatic battery management.
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 continuous use of HMDs without interrupting the user experience, reduces weight, and eliminates cable connection troubles, while preventing terminal corrosion, thus enhancing usability and safety.
Implementation Method 1
power is supplied from a power transmission coil of the charger to a power receiving coil of the electronic glasses by inductive coupling to charge a battery
Implementation Method 2
a power transmission coil that transmits power wirelessly to the HMD; a power receiving coil that receives the power transmitted by the power transmission coil by electromagnetic induction
Data Source
AI summary
An HMD includes first and second batteries mounted therein, and includes a plurality of power receivers that receive power from the first and second batteries by wireless transmission, a power supply manager that monitors states of the first and second batteries, a communication interface that performs wireless communication with the first and second batteries, and a plurality of limiters that limit the power received by the plurality of power receivers. A controller causes the limiters to limit power, which is supplied to a load, according to a power use state of the load in the device, and the power supply manager acquires information of remaining power storage amounts of the first and second batteries through the communication interface and displays the acquired information on a display. Therefore, since it is possible to supply power required for driving the device while wearing the HMD, the HMD can be continuously used.