Capacitive Scanner Sensor Exterior Mounting for Interference Reduction
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Solution Overview
Problem
Conventional scanners for detecting objects behind opaque surfaces face issues with sensitivity and accuracy due to the placement of capacitive sensors inside the housing, which can be displaced and cause electromagnetic interference with metal sensors, requiring recalibration and a minimum separation distance.
Innovation Solution
The capacitive sensors are attached to the exterior surface of the housing, using conductive rubber or ink, reducing electromagnetic interference and allowing for improved sensitivity and accuracy by shortening the distance to the object and eliminating the need for recalibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If capacitive sensors are attached inside the housing on the PCB, then the scanner structure is compact and sensors are protected, but the sensitivity and accuracy are reduced due to increased distance from the object and potential displacement
Solution Approach 1:
The capacitive sensors are extracted from the internal PCB mounting and repositioned to the exterior surface of the housing. This extraction allows the sensors to be placed closer to the detection surface, improving sensitivity and accuracy without the constraints of internal space and PCB layout requirements.
Solution Approach 2:
The sensor placement transitions from a two-dimensional PCB surface to the three-dimensional exterior surface of the housing. This dimensional change enables optimal positioning of sensors at the closest possible distance to the object being detected, maximizing capacitive coupling and detection accuracy.
2Volume of moving object
If capacitive sensors are placed close to metal sensors on the PCB, then device size is reduced, but electromagnetic interference increases reducing metal detection accuracy
Solution Approach 1:
The capacitive sensors are extracted from the PCB and moved to the exterior housing surface. This spatial separation eliminates the electromagnetic interference issue that would occur if capacitive sensors were placed near metal sensors on the PCB, while still maintaining a compact overall device size.
Solution Approach 2:
The housing exterior surface acts as an intermediary medium between the capacitive sensors and the target object. This allows the sensors to be positioned optimally for detection while physically separating them from metal sensors inside the housing, preventing electromagnetic interference.
3Ease of manufacture
If capacitive sensors are mounted on PCB inside housing, then manufacturing is simplified, but recalibration is required after accidental drops due to PCB displacement
Solution Approach 1:
By extracting the capacitive sensors from the PCB and mounting them directly to the housing exterior, the system eliminates the recalibration issue caused by PCB displacement during drops. The sensors remain fixed in their optimal positions relative to the detection surface.
Solution Approach 2:
The design anticipates potential drops and PCB displacements by mounting capacitive sensors to the rigid housing structure rather than the flexible PCB. This beforehand protection ensures sensor positions remain stable under shock conditions, preventing the need for recalibration.
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 configuration enhances the scanner's sensitivity and accuracy, reduces material costs, and provides more reliable object detection with improved signal dynamic range, even in the presence of construction anomalies.
Implementation Method 1
the capacitive sensor(s) 108, which can be configured to detect a change in capacitance in response to a presence of the object 101
Implementation Method 2
the capacitive sensor(s) 108, formed with copper plates, can create electromagnetic interference with the metal sensors
Data Source
AI summary
Method and apparatus are provided for detecting objects behind an opaque surface. An exemplary device for detecting objects behind an opaque surface, comprising a housing configured to hold a plurality of components of the device; one or more sensors, coupled to the housing, configured to collect sensor data of an object behind the opaque surface, where the one or more sensors include one or more capacitive sensors attached to an exterior surface of the housing; a controller, residing inside the housing, configured to process the sensor data collected by the one or more sensors; an at least one printed circuit board, residing inside the housing, configured to hold the controller and the plurality of components of the device; and a display configured to convey information about a detected object to a user.