Resonant RF Face Tracking Circuit With Edge-Sampled Sensing
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Solution Overview
Problem
Conventional LC resonant drive circuits for face tracking in MR devices require high power consumption and large circuit area due to the need for high signal amplitude and bulky inductors to achieve sufficient resolution and sensitivity.
Innovation Solution
A novel resonant drive and sampling scheme that integrates a driver circuit, LC resonance circuit, and sample and hold circuit to capture and amplify signal differences at the falling edge of the control signal, reducing the need for bulky inductors and achieving high sensitivity with reduced power consumption and circuit area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional LC resonant drive circuits use high power supply levels to maximize signal amplitude, then measurement precision is improved, but use of energy deteriorates
Solution Approach 1:
The patent applies periodic action by using pulsed drive signals instead of continuous high-power signals. The driver circuit generates periodic pulses that excite the LC resonance circuit, allowing the system to accumulate energy over multiple cycles while maintaining high signal amplitude during measurement. This periodic excitation reduces average power consumption compared to continuous high-power operation.
Solution Approach 2:
The patent changes the parameter of drive signal characteristics by using variable pulse width and duty cycle control. The driver circuit adjusts the pulse parameters dynamically to optimize the balance between signal amplitude and power consumption. By controlling the pulse duration and frequency, the system achieves sufficient signal strength for accurate measurement while minimizing energy consumption during idle or low-signal conditions.
2Measurement precision
If conventional LC resonant drive circuits use bulky inductors to achieve sufficient resolution, then measurement precision is improved, but area of stationary object deteriorates
Solution Approach 1:
The patent extracts the inductor from the traditional LC resonance circuit configuration. Instead of using a physical inductor component, the system uses the inherent inductance of the sense antenna itself as the L component. This eliminates the need for separate bulky inductor components, significantly reducing circuit area while maintaining the resonance functionality and measurement precision.
Solution Approach 2:
The patent applies multi-functionality by using the sense antenna to serve dual purposes: both as the sensing element for detecting facial movements and as the inductive component (L) of the LC resonance circuit. This eliminates the need for dedicated inductor components, reducing overall circuit area while maintaining resolution through the antenna's natural inductance characteristics.
3Device complexity
If conventional LC resonant drive circuits use high power supply levels, then device complexity is reduced, but manufacturing cost deteriorates
Solution Approach 1:
The patent extracts and eliminates the bulky inductor component from the circuit design, using only the antenna's inherent inductance. This simplifies the bill of materials and reduces component count, making the device easier and cheaper to manufacture while maintaining circuit functionality and measurement precision.
Solution Approach 2:
The patent applies local quality by utilizing the unique electrical characteristics of the sense antenna at its specific location. The antenna's inherent inductance and capacitance are leveraged to form the LC resonance circuit, eliminating the need for additional discrete components. This approach reduces manufacturing complexity and cost while maintaining the required device performance.
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
The scheme achieves high sensitivity and reduced cost without bulky inductors, maintaining high sensitivity for RF face tracking while minimizing power consumption and circuit size.
Implementation Method 1
The antennas signals may feed into an LC resonance circuit, which is driven to a resonance by an LC driver
Implementation Method 2
The self-oscillating circuit includes the first electrode and the second electrode. In an embodiment, the first electrode is a first plate in a capacitor structure and the second electrode is a second plate in the capacitor structure
Data Source
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AI summary
A system for facial movement detection with reduced size and reduced cost by employing a novel resonant drive and sampling scheme is disclosed. An example battery operated system includes a driver circuit, an LC resonance circuit formed by an inductor circuit and a capacitance from an antenna, and a sample and hold circuit. The driver circuit can be configured by a controller to generate a drive signal for the LC resonance circuit, which has a resonant frequency that changes as the capacitance of the antenna varies responsive to facial movements of the user. The sample and hold circuit samples the output of the LC resonance circuit responsive to a falling edge of the drive signal for the LC resonance circuit, wherein an output of the sample and hold circuit is a sampled sense signal that may be further processed to detect facial movements of the user.