RF Digital Key Backup Charging for Depleted Phone Batteries
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Solution Overview
Problem
Mobile devices with depleted batteries cannot perform RF transactions, such as unlocking a car door, due to high power demands and low antenna coupling with RF fields, making it impractical to power them using an RF field for digital key functions.
Innovation Solution
Incorporating a backup power source, like a super-capacitor, that can be charged by an RF field generated by a reader device, allowing the mobile device to perform RF transactions even with a depleted main battery by using the stored energy for short-term power needs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mobile device uses a depleted main battery, then the device cannot perform RF transactions due to insufficient power, but adding a backup power source increases device complexity
Solution Approach 1:
The backup power source is charged in advance through wireless power transfer from the reader device before the RF transaction is needed. This preliminary charging action ensures power availability without requiring the user to manually recharge the battery, resolving the contradiction by preparing the power source beforehand.
Solution Approach 2:
A backup power source acts as an intermediary energy buffer between the depleted main battery and the power-hungry RF transaction components. This intermediary component temporarily stores and supplies the necessary power during the transaction, enabling operation without increasing overall system complexity.
2Use of energy by moving object
If the mobile device receives RF power from a reader, then power can be supplied to the device, but the received RF power level is too low to meet the high power demand of RF transactions
Solution Approach 1:
The reader device performs preliminary wireless charging of the backup power source before the RF transaction. This advance power transfer accumulates sufficient energy in the backup source to meet the high power demands of the transaction, overcoming the limitation of low instantaneous RF power reception.
Solution Approach 2:
The power supply function is segmented into two distinct components: the main battery for normal operation and the backup power source for emergency RF transactions. This segmentation allows the backup source to be specifically optimized for high-power transaction needs without affecting the main battery's regular charging cycle.
3Loss of energy
If the mobile device has low antenna coupling with RF fields, then wireless power transfer efficiency is reduced, but optimizing antenna coupling increases device complexity
Solution Approach 1:
Wireless power transfer to charge the backup power source is performed in advance when the device can remain stationary near the reader for an extended period. This preliminary action compensates for low antenna coupling efficiency by allowing more time for energy transfer, avoiding the need for complex antenna optimizations.
Solution Approach 2:
The backup power source is designed as a temporary, short-term energy buffer rather than a permanent power solution. This disposable-like approach accepts lower charging efficiency since the backup source only needs to be charged occasionally for brief transactions, eliminating the need for expensive, highly efficient antenna systems.
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 mobile devices to perform RF transactions, including authentication and access, even when the main battery is depleted, by providing sufficient power through a charged backup source, overcoming the limitations of low received RF power and high power requirements.
Implementation Method 1
a backup power source, like a super-capacitor, that can be charged by an RF field generated by a reader device
Data Source
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AI summary
For a mobile device having a main battery and a backup power source, a method is provided for wirelessly charging the backup power source using a reader when the main battery of the mobile device is fully depleted and unable to provide enough power for an RF transaction. The reader detects the mobile device cannot perform the RF transaction. In response, the reader generates an RF field that provides charge for the backup power source of the mobile device. After charging is complete, the mobile device performs the RF transaction using the charged backup power source. In one embodiment the mobile device is a mobile phone being used as a digital key and the reader is implemented in a smart door handle of an automobile that is unlocked by the RF transaction.