Earbud Antenna Impedance Measurement for Compact Gesture Input
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Solution Overview
Problem
Electronic devices with wireless capabilities face challenges in providing a small form factor while accommodating both wireless circuitry and user input devices, as user input devices like capacitive sensors occupy significant space and exhibit high latency.
Innovation Solution
Utilize antennas to detect user input gestures by measuring impedance changes in multiple frequency bands, eliminating the need for bulky capacitive sensors by employing signal couplers and impedance processors to analyze antenna impedance variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If user input devices like capacitive sensors are used, then gesture detection capability is provided, but device space is excessively occupied and latency is high
Solution Approach 1:
The antenna is made multi-functional by enabling it to perform both its original wireless communication function and a new gesture detection function. The same antenna structure is used to transmit radio-frequency signals and to detect impedance changes caused by user gestures, eliminating the need for separate capacitive sensor components.
Solution Approach 2:
The gesture detection function is merged with the existing wireless circuitry by using the antenna and its associated radio-frequency transmission line. The impedance measurement circuit is integrated into the existing wireless communication path, combining multiple functions into a unified system that reduces overall device volume.
2Ease of operation
If user input devices like capacitive sensors are used, then gesture detection capability is provided, but detection latency is high
Solution Approach 1:
The system continuously monitors antenna impedance during normal radio-frequency signal transmission without requiring separate measurement cycles. The impedance changes are detected in real-time as the radio-frequency signal continuously interacts with the antenna and surrounding environment, enabling low-latency gesture detection.
Solution Approach 2:
The antenna itself serves as the sensing element for gesture detection, using its own radio-frequency signal to probe for impedance changes. The existing radio-frequency transmission automatically performs the detection function without requiring additional external sensors or separate measurement systems.
3Measurement precision
If separate gesture detection components are added, then gesture recognition accuracy is improved, but device complexity increases
Solution Approach 1:
The antenna is made multi-functional by enabling it to perform both its original wireless communication function and a new gesture detection function. The same antenna structure is used to transmit radio-frequency signals and to detect impedance changes caused by user gestures, eliminating the need for separate capacitive sensor components.
Solution Approach 2:
The system uses feedback from impedance measurements to detect gesture events. The processor continuously monitors impedance changes and compares them against threshold values or patterns to identify specific gestures, providing accurate gesture recognition through a simple feedback mechanism rather than complex multi-sensor arrays.
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 compact device design with reduced latency in detecting user input gestures, minimizing space and weight while maintaining efficient gesture recognition.
Implementation Method 1
One or more processors may measure the impedance of the antenna(s) in at least the high and low bands using the signal coupler(s) and the transmitted radio-frequency signal
Implementation Method 2
One or more signal couplers may be disposed along the transmission line path(s)
Data Source
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AI summary
A wireless earbud (10) may have a head (82) and a stalk (84). A speaker (70) may be disposed in the head (82). An antenna (30) may be disposed in the stalk (84). One or more radios (26) may transmit a radio-frequency signal in high and low bands over high and low band arms of the antenna (30). A signal coupler (34) may be coupled to the antenna (30). The signal may include scheduled transmission blocks and optionally unscheduled transmission blocks. A processor (36) may measure impedance of the antenna (30) in the high and low bands using the signal coupler (34) and the transmitted signal. The processor (36) may detect a gesture based on an order of changes in the impedance in the high and low bands. The processor (36) may take suitable action based on the detected gesture. The gesture may include, for example, a volume up or down gesture in implementations where the high and low band arms extend parallel to the stalk (84).