Capacitance Module Shield Layout for RF and Haptic Isolation
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Solution Overview
Problem
Capacitive touch pads on processor-based devices interfere with radio frequency transmissions due to electrical shielding, leading to difficult antenna tuning, increased power consumption, and manufacturing challenges.
Innovation Solution
A capacitance module with a magnetically conductive, electrically insulating barrier between the antenna and haptic actuator, along with an electrically conductive shield, to prevent eddy currents and allow radio frequency transmission while maintaining touch pad functionality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electrical shielding is added to prevent noise interference with the capacitive touch pad, then touch pad functionality is improved, but radio frequency transmission and reception are blocked
Solution Approach 1:
The shielding structure is divided into multiple segments: a first shield connected to the touch pad ground plane and a second shield connected to the antenna ground plane, with a gap between them. This segmentation allows the shield to prevent noise interference while permitting radio frequency signals to pass through the gap, thus resolving the contradiction between touch pad reliability and radio frequency transmission.
Solution Approach 2:
The shield structure has different properties in different locations: the first shield portion provides electrical shielding for the touch pad area, while the second shield portion provides shielding for the antenna area, with a specific gap configuration between them. This local differentiation allows each region to have the appropriate shielding characteristics for its function, enabling both touch pad reliability and radio frequency transmission.
2Area of stationary object
If the antenna is placed near the capacitive touch pad, then device space is optimized, but antenna tuning becomes difficult and performance is affected
Solution Approach 1:
The shield is segmented into two distinct portions with a gap between them, allowing the antenna to be positioned close to the touch pad while the gap maintains proper electromagnetic isolation. This enables compact device design without compromising antenna performance or requiring extensive tuning adjustments.
3Object-affected harmful factors
If shielding is implemented to protect the capacitive touch pad, then noise interference is reduced, but power consumption increases
Solution Approach 1:
The segmented shield structure with a gap between the first and second shield portions provides noise protection for the capacitive touch pad while allowing radio frequency signals to pass through. This configuration reduces the shielding effectiveness compared to a continuous shield, thereby reducing power consumption while still maintaining adequate noise protection.
4Area of stationary object
If the antenna and haptic actuator are placed close together, then device compactness is improved, but eddy currents are generated in the haptic actuator
Solution Approach 1:
A magnetically conductive and electrically insulating material is placed between the antenna and the haptic actuator. This intermediary material provides a path for magnetic field lines while blocking electrical eddy currents, enabling compact device design without generating harmful eddy currents in the haptic actuator.
Solution Approach 2:
The use of magnetically conductive and electrically insulating composite materials (such as ferrite) between the antenna and haptic actuator allows the device to maintain compact dimensions while preventing eddy current generation. The composite material simultaneously conducts magnetic fields and insulates against electrical currents.
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
Enhances radio frequency transmission efficiency, reduces power consumption, and simplifies manufacturing by minimizing interference between capacitive touch pads and radio transceivers.
Implementation Method 1
a magnetically conductive, electrically insulating barrier between the antenna and the haptic actuator... preventing and/or reducing the formation of eddy currents in the haptic actuator by at least reducing an influence a magnetic field generated by the antenna from affecting the haptic actuator
Implementation Method 2
the antenna may be configured to transmit a wireless signal according to a Wi-Fi protocol... the antenna may be configured to transmit a wireless signal according to a short-range wireless protocol... the antenna may be configured to transmit a wireless signal according to a Near Field Communication (NFC) protocol
Implementation Method 3
The haptic actuator may include at least one piezoelectric element
Implementation Method 4
capacitive touch pads often require electrical shielding to prevent noise from the processor-based device from interfering with normal touch pad functions
Data Source
AI summary
A capacitance module may include at least one capacitive sensor layer; an antenna connected to the capacitive sensor layer; and at least one haptic actuator connected to the capacitive sensor layer.