Capacitive Touch Interface Assembly With Biasing Contact Through Thick Glass
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Solution Overview
Problem
Industrial process transmitters in corrosive, explosive, and vibrating environments require explosion-proof designs with rugged housings and thick glass covers, which hinder capacitive touch signal strength due to air gaps and potential damage from cover torque or vibration.
Innovation Solution
A capacitive touch interface assembly with a display shroud and electronics board shroud connected via a biasing member, allowing axial displacement and rotation, and capacitive touch circuitry embedded in the shroud to eliminate air gaps and maintain physical contact with a transparent cover, ensuring reliable touch actuation without exposing internal components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick glass cover is used to create an explosion-proof enclosure, then safety and protection are improved, but capacitive touch signal strength deteriorates due to air gaps
Solution Approach 1:
The patent removes the air gap between the cover and the display assembly by extracting the problematic space, allowing the glass cover to directly contact the display surface, thereby maintaining capacitive touch sensitivity while preserving explosion-proof protection
Solution Approach 2:
The display assembly is pre-configured with a flat mounting surface and integrated support structures that ensure direct contact with the cover before final assembly, eliminating the need for post-assembly adjustments and preventing air gap formation
2Strength
If the cover is made rigid and thick for protection, then structural strength is improved, but the cover becomes susceptible to damage from torque and vibration
Solution Approach 1:
The patent incorporates compliant mounting features and flexible connections between the display assembly and housing that absorb and dampen mechanical shocks, vibrations, and torque forces before they can damage the rigid glass cover
Solution Approach 2:
The display assembly includes flexible circuit boards and compliant mounting structures that allow the rigid display components to be mounted on a slightly flexible substrate, enabling the assembly to flex slightly under vibration and torque without breaking the glass cover
3Ease of operation
If programming devices are transported to installation location for configuration, then configuration capability is improved, but cost and operational complexity increase
Solution Approach 1:
The display assembly serves multiple functions: it provides the user interface for operation, serves as the configuration interface for programming, and acts as the sealed front of the housing, eliminating the need for separate programming devices and reducing overall system complexity
Solution Approach 2:
The transmitter can be configured through its own built-in display and touch interface, allowing operators to program and configure the device directly at the installation location without requiring external programming tools
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 capacitive touch sensitivity by eliminating air gaps and reducing the risk of damage from environmental factors while maintaining an explosion-proof and sealed enclosure.
Implementation Method 1
the biasing member is configured to urge the contact structure of the display shroud into physical contact with the transparent cover piece
Implementation Method 2
a touch circuit for providing touch actuation at or near the digital display through the transparent cover piece
Data Source
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AI summary
A display assembly includes a transparent cover piece (62), a display shroud (48; 248) having a contact structure (74; 274) arranged to face the transparent cover piece (62), an interface subassembly (32; 232) mounted on the display shroud (48; 248), an electronics board shroud (44) having a support member (82) and a connection feature (84), and a biasing member (46) operably engaged between the display shroud (48; 248) and the electronics board shroud (44). The connection feature (84) mechanically connects the electronics board shroud (44) to the display shroud (48; 248) while permitting axial displacement and rotation therebetween. The biasing member (46) rests on the support member (82) of the electronics board shroud (44), and the biasing member (46) is configured to urge the contact structure (74; 274) of the display shroud (48; 248) into physical contact with the transparent cover piece (62). The interface subassembly (32; 232) includes a display circuit (36) for providing a digital display and a touch circuit (34) for providing touch actuation at or near the digital display through the transparent cover piece (62).