Capacitive Touch Interface Through Explosion-Resistant Instrument Housings
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Solution Overview
Problem
Existing explosion-resistant process control devices require costly and time-consuming maintenance procedures due to their sealed nature, limiting access and flexibility in input options, and existing communication methods like optical and magnetic systems are power-constrained and unreliable in hazardous environments.
Innovation Solution
A touch sensor interface allows users to communicate with the controller without decommissioning the device, providing flexible and power-efficient input options, including discrete and non-discrete inputs, and is capable of operating in environments unsuitable for optical sensors, with a transparent portion and touch sensor configuration that can withstand explosive pressures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If optical systems are used for communication with the controller, then input capability is provided, but power consumption is high and reliability is reduced due to power constraints and sensitivity to environmental contaminants
Solution Approach 1:
The patent replaces optical systems with a capacitive touch sensor system that uses electrical fields rather than light. The touch sensor detects changes in capacitance when a user touches the transparent portion of the enclosure, providing input capability without the power consumption and reliability issues of optical systems. This substitution of detection mechanism resolves the contradiction by maintaining input functionality while eliminating sensitivity to environmental contaminants and reducing power requirements.
Solution Approach 2:
The patent changes the detection parameter from optical reflection to electrical capacitance. By measuring capacitance changes at the touch interface rather than detecting reflected light, the system achieves more reliable operation in hazardous environments. The capacitive detection method is not affected by dirt, grime, or other environmental contaminants that would interfere with optical systems, thereby improving reliability while maintaining ease of operation.
2Strength
If explosion resistant sealed containers are used, then protection against explosive forces is provided, but access to components is prevented and maintenance becomes time-consuming and costly
Solution Approach 1:
The patent introduces a transparent portion of the enclosure that serves as an intermediary interface between the user and the controller inside the sealed explosion-resistant container. This transparent interface allows capacitive touch input to be transmitted through the enclosure wall without breaching the seal. The intermediary maintains the explosion-proof integrity while enabling maintenance and operation without decommissioning the device.
Solution Approach 2:
The patent replaces physical access mechanisms (buttons, switches, or open interfaces) with a capacitive touch sensor system that operates through the sealed transparent enclosure. This eliminates the need to open or breach the explosion-resistant container for maintenance or operation, as all interactions occur through the capacitive interface that penetrates the seal electrically rather than mechanically.
3Ease of operation
If optical sensors are used for each input, then input detection is enabled, but device complexity increases and power consumption rises due to the number of sensors required
Solution Approach 1:
The patent implements a universal capacitive touch sensor system where a single sensor array can detect multiple input locations and gestures across the entire transparent enclosure surface. Rather than requiring separate optical sensors for each input point, the capacitive system provides multi-functional input detection across the whole interface area, reducing both device complexity and power consumption while maintaining ease of operation.
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
Enables on-the-fly adjustment of operating parameters without decommissioning the device, offering increased design versatility and reliability by consuming less power and maintaining functionality despite environmental contaminants like dirt and grime.
Implementation Method 1
a touch sensor, such as a capacitive touch sensor
Data Source
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AI summary
An apparatus includes a housing, a touch sensor, a display, and a control module. The housing has a body defining a volume to accommodate a process control device and is adapted to withstand a threshold internal pressure greater than an external pressure. The housing further has a transparent portion having first and second surfaces. The touch sensor is disposed adjacent to the second surface of the transparent portion and senses an input received within a minimum distance from the first surface of the transparent portion. The display is disposed adjacent to the touch sensor and displays at least one adjustable variable corresponding to the process control device.