Resonant RF Face Tracking Drive With Duty Cycle Amplitude Control
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Solution Overview
Problem
Conventional face tracking systems in MR wearable devices consume high power due to the need for large signal processing and power-hungry operational amplifiers, which limits battery life and device portability.
Innovation Solution
A digitally controlled resonant drive circuit generates an alternating current input signal to drive face tracking sensors, adjusting the duty cycle based on output signal amplitude to maintain a target amplitude, reducing power consumption and eliminating linear power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional face tracking systems use large signal processing and power-hungry operational amplifiers, then signal processing capability is improved, but power consumption increases
Solution Approach 1:
The patent applies resonant drive at a specific frequency (e.g., 100 kHz) to the capacitive sensor, causing the sensor to operate at its resonant frequency where it naturally produces larger output signals. This resonance effect amplifies the sensor output without requiring additional power-hungry signal processing amplifiers, thus resolving the contradiction between signal processing capability and power consumption
Solution Approach 2:
The patent changes the operating parameters by driving the capacitive sensor with a resonant frequency AC signal instead of conventional DC or low-frequency signals. This parameter change causes the sensor to operate in a resonant state, naturally producing larger output signals that require less amplification, thereby reducing power consumption while maintaining signal processing capability
2Measurement precision
If face tracking sensors are driven with conventional signals, then device simplicity is maintained, but output signal amplitude is insufficient
Solution Approach 1:
By driving the capacitive sensor at its resonant frequency, the sensor naturally produces larger output signals due to resonant amplification. This approach achieves high output signal amplitude without adding complex signal processing circuitry, as the resonance effect provides the amplification naturally
Solution Approach 2:
The patent implements a feedback mechanism where the output signal amplitude is monitored and compared to a target amplitude, and the duty cycle of the resonant drive is adjusted accordingly. This feedback control maintains optimal signal amplitude while keeping the overall system relatively simple by using duty cycle modulation rather than complex amplification circuits
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 approach achieves a large output signal amplitude with low power consumption, prolonging battery life and enabling compact, portable MR wearable devices.
Implementation Method 1
A resonant drive circuit generates an alternating current (AC) input signal
Data Source
AI summary
A system and method generate an alternating current (AC) input signal by a digitally controlled resonant drive circuit. The method includes driving a face tracking sensor with the input signal. An output signal is received from the face tracking sensor and an amplitude of the output signal is compared to a target amplitude. A duty cycle of the resonant drive circuit is modified based on the comparison to control the amplitude of the output signal about the target amplitude.