Ultrasonic Proximity Sensor Barrier Layout for Accurate Detection
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Solution Overview
Problem
Existing ultrasonic proximity sensors in electronic devices face challenges in distinguishing between direct and reflected ultrasonic signals, leading to inaccurate proximity detection due to direct signal interference, which affects the device's ability to ignore inputs when held next to the user's head.
Innovation Solution
The implementation of an ultrasonic proximity sensor arrangement with a barrier between the transmitter and receiver to attenuate direct signals, allowing only reflected signals to propagate effectively, along with the use of acoustically attenuating materials and structured signal paths to enhance signal-to-noise ratio and prevent direct signal interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the ultrasonic transmitter and receiver are placed close to each other to achieve compact form factor, then the device size is reduced, but direct path signals interfere with reflected signal detection reducing measurement precision
Solution Approach 1:
The patent divides the acoustic space by introducing a barrier structure that segments the path between transmitter and receiver. This barrier creates separate direct and reflected signal paths, allowing the system to maintain compact dimensions while preventing direct path interference from contaminating the reflected signal measurement.
Solution Approach 2:
The patent introduces a barrier as an intermediary element between the ultrasonic transmitter and receiver. This barrier selectively blocks direct path signals while allowing reflected signals to reach the receiver, thereby mediating the interaction between the transmitter and receiver to achieve both compact size and accurate proximity detection.
2Measurement precision
If a barrier is introduced to block direct path signals and improve measurement precision, then proximity detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent employs a thin film or baffle as the barrier structure, which provides effective acoustic blocking of direct path signals while maintaining a simple, lightweight construction. This thin barrier introduces minimal structural complexity compared to more substantial shielding mechanisms.
Solution Approach 2:
The patent utilizes porous or acoustically absorptive materials for the barrier structure, which effectively attenuate direct path ultrasonic signals while allowing the barrier to remain relatively simple in construction. These materials provide acoustic filtering without requiring complex geometric configurations.
3Measurement precision
If the barrier extends to the front surface to completely block direct signals, then direct path attenuation is maximized, but reflected signals from objects close to the surface may be completely blocked
Solution Approach 1:
The patent applies partial blocking rather than complete blocking of the direct path. The barrier is positioned to provide sufficient attenuation of direct signals without extending fully to the front surface, thereby maintaining an acoustic path that allows reflected signals from objects near the surface to reach the receiver.
Solution Approach 2:
The patent positions the barrier in a specific spatial dimension between the transmitter and receiver, creating a three-dimensional acoustic pathway configuration. This dimensional arrangement allows direct signals to be blocked while preserving volumetric space for reflected signals to propagate around or through the barrier structure.
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 solution improves the accuracy of proximity detection by reducing direct signal interference, allowing for reliable operation even when the device is close to the user's head, and enables the use of existing microphone and speaker hardware for active noise cancellation.
Implementation Method 1
a barrier extending between the transmitter and receiver in the direction of the front surface of the device... helps to attenuate ultrasonic signals travelling directly from the transmitter to the receiver
Implementation Method 2
an ultrasonic transmitter recessed from a front surface of the device... a signal transmitted from the ultrasonic transmitter
Implementation Method 3
the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter
Data Source
AI summary
An electronic device (202) includes an ultrasonic proximity sensor arrangement comprising an ultrasonic transmitter (4) and an ultrasonic receiver (6) recessed from a front surface (208) of the device. A barrier (218) extends between the transmitter and receiver in the direction of the front surface of the device. The ultrasonic proximity sensor arrangement is arranged to determine proximity of an object (16) to said front surface based on a signal (214) received by the ultrasonic receiver, wherein the received signal is a reflection from said object of a signal transmitted from the ultrasonic transmitter.