Ground-Shielded Proximity Sensor Layout for RF Interference
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Solution Overview
Problem
Proximity sensors in motor vehicles face challenges in maintaining performance due to the need for a large surface area and close proximity to users, which can be compromised by the presence of electrical and electronic components, leading to degraded sensor performance.
Innovation Solution
A proximity sensor design featuring a substrate with a transmit electrode and spaced receive electrodes, incorporating a ground shield portion to reduce electric field attenuation by conducting objects, allowing for sensitive detection of conducting objects in two dimensions and enabling integration with other components without significant performance degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the sensor is located close to the user to enable triggering without undue movement, then the ease of operation is improved, but the sensor performance is degraded due to interference from electrical and electronic components
Solution Approach 1:
The sensor is divided into multiple sensor portions (first, second, and third sensor portions) arranged in a specific configuration. This segmentation allows the sensor to maintain close proximity to the user for ease of operation while distributing the detection function across multiple portions, reducing interference from surrounding electronic components and maintaining reliable performance.
Solution Approach 2:
A ground shield portion is introduced as an intermediary element between the sensor portions and the conducting objects (electrical components). This ground shield acts as a mediator that reduces electric field attenuation caused by conducting objects, thereby protecting the sensor performance while allowing the sensor to remain close to the user for easy operation.
2Measurement precision
If the sensor surface area is increased to improve detection sensitivity, then the measurement precision is improved, but the device complexity increases
Solution Approach 1:
The sensor utilizes a three-dimensional configuration with sensor portions arranged in multiple dimensions rather than simply increasing the surface area of a single planar sensor. The first, second, and third sensor portions are positioned at different locations and orientations, enabling sensitive detection in multiple directions while maintaining a compact overall structure, thus improving detection sensitivity without significantly increasing device complexity.
3Adaptability or versatility
If more electrical and electronic components are integrated into the cockpit, then the functionality is improved, but the sensor performance is degraded due to increased interference
Solution Approach 1:
The ground shield portion is strategically positioned between the sensor portions and the conducting objects (electrical components) to provide localized shielding where it is most needed. This local quality approach allows the sensor to coexist with multiple electrical and electronic components in the cockpit, maintaining sensor performance while enabling increased system functionality.
4Reliability
If the ground shield portion is positioned between the receive electrodes and the conducting objects, then the electric field attenuation is reduced, but the device complexity increases
Solution Approach 1:
The ground shield portion is merged with the substrate or housing structure of the sensor assembly, integrating the shielding function into the existing structural components rather than adding it as a separate element. This merging approach reduces electric field attenuation while minimizing the increase in device complexity by utilizing existing structural elements for multiple functions.
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 sensor design effectively reduces electric field attenuation by conducting objects, enhancing sensitivity and allowing for higher component packaging densities in motor vehicle applications while maintaining reliable detection of object movement.
Implementation Method 1
The sensor is arranged with a substantially planar transmit electrode provided over a rear face of the sensor substrate and a first and a second substantially planar receive electrode provided over a front face of the sensor substrate. The sensor is arranged to generate an electric field extending in front of the sensor substrate.
Implementation Method 2
The sensor further comprises a ground shield portion provided between the first and second receive electrodes. The ground shield portion is arranged to reduce attenuation of the electric field by conducting objects.
Implementation Method 3
The sensor being configured to allow a radio frequency (RF) signal to be applied to the transmit electrode to cause a corresponding RF signal to be induced in each receive electrode wherein the relative strength of the RF signals induced in the receive electrodes is dependent on the relative distance of a conducting object therefrom.
Data Source
AI summary
Some embodiments of the present invention provide a proximity sensor (300) comprising: at least a first sensor portion, a second sensor portion and a third sensor portion, the second sensor portion being provided between the first and third sensor portions, the first and third sensor portions each comprising at least a portion of a or a respective substrate (310) having first and second opposite major faces, the first and third sensor portions each bearing on a major face of the or the respective substrate at least a portion of a substantially planar transmit electrode (320), and a substantially planar receive electrode (330A, 330B) arranged to receive a signal transmitted by the respective at least a portion of a transmit electrode, the second sensor portion comprising a first region (315), the sensor comprising a ground shield portion (340) comprising one or more substantially planar, elongate electrodes, the ground shield portion having at least one elongate portion laterally disposed between the receive electrode of the first sensor portion and the first region of the second sensor portion, and at least one elongate portion disposed between the first region of the second sensor portion and the receive electrode of the third sensor portion, the sensor (300) being configured to allow a radio frequency (RF) signal to be applied to the transmit electrode (320) to cause a corresponding RF signal to be induced in each receive electrode (330A-D), the relative strength of the RF signals induced in the receive electrode (330A-D) of the respective portions being responsive to the relative distance of a conducting object therefrom.