Opaque-Surface Scanner with External Capacitive Sensors for EMI Control
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Solution Overview
Problem
Conventional scanners for detecting objects behind opaque surfaces face issues with suboptimal sensitivity and accuracy due to the placement of capacitive sensors on a printed circuit board (PCB), which can be displaced, require a minimum separation from metal sensors to avoid electromagnetic interference, and need recalibration after drops.
Innovation Solution
The capacitive sensors are externally coupled to the housing, using conductive rubber materials that minimize electromagnetic interference, allowing for reduced size and improved accuracy, and the scanner can detect changes in dielectric constants to locate objects accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If capacitive sensors are attached to the PCB inside the housing, then the device structure is simplified, but the sensitivity and measurement precision are reduced due to suboptimal placement and possible PCB displacement
Solution Approach 1:
The capacitive sensors are extracted from the internal PCB structure and repositioned to the external surface of the housing. This allows the sensors to be optimally positioned for detecting objects behind opaque surfaces while maintaining a simplified internal PCB structure for other components.
Solution Approach 2:
The sensors transition from being constrained to the two-dimensional PCB plane inside the housing to being positioned on the external three-dimensional surface of the housing, enabling optimal placement for detection sensitivity without compromising internal structural simplicity.
2Volume of moving object
If capacitive sensors are placed close to metal sensors on the PCB, then the device size is reduced, but electromagnetic interference increases reducing measurement precision
Solution Approach 1:
The capacitive sensors are extracted from the internal PCB where they would be in close proximity to metal sensors, and repositioned on the external housing surface. This spatial separation eliminates electromagnetic interference while maintaining a compact overall device design.
3Ease of manufacture
If capacitive sensors are internally mounted on PCB, then manufacturing is easier, but recalibration is required after accidental drops due to PCB displacement
Solution Approach 1:
The capacitive sensors are extracted from the vulnerable internal PCB mounting and repositioned to the external housing surface where they are protected from displacement during handling and accidental drops, eliminating the need for recalibration while maintaining manufacturing simplicity.
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 external placement of capacitive sensors with conductive rubber reduces electromagnetic interference, enhances sensitivity and accuracy, and minimizes the need for recalibration, improving the scanner's performance in detecting objects behind opaque surfaces.
Implementation Method 1
capacitive sensor(s) 108 configured to measure a change in capacitance caused by the presence of the object behind the opaque surface
Implementation Method 2
detect changes in dielectric constants to locate objects accurately
Implementation Method 3
The capacitive sensor(s) 108, formed with copper plates, can create electromagnetic interference with the metal sensors
Data Source
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Figure 3A
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, a controller, residing inside the housing, configured to process the sensor data collected by the one or more sensors, 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.