Local User Interface for Explosion Resistant Field Instruments Using Capacitive Touch Sensing

A method of manufacturing a process control device, the method comprising:

• providing a housing having a body defining a volume to encapsulate a controller that controls operation of a field device, and adapted to withstand a threshold internal pressure greater than an external pressure, the body further having a transparent portion having a first surface and a second surface;
• at least partially disposing the controller device in the volume of the housing;
• disposing a touch sensor adjacent to the second surface of the transparent portion;
• disposing a display adjacent to the touch sensor;
• coupling a control module to the touch sensor and the display;
• and
• sealing the housing such that the controller is.

An apparatus comprising:

• a first housing having a body defining a volume to encapsulate a process control device;
• a second housing having a body defining a volume to encapsulate the first housing, the second housing being capable of withstanding a threshold internal pressure greater than an external pressure;
• an interface coupled to at least one of the first housing or the second housing;
• a touch sensor disposed adjacent to the interface, the touch sensor adapted to sense an input received within a minimum distance from the interface;
• a display disposed adjacent to the sensor;
• and
• a control module disposed within the first housing, the control module being coupled to the touch sensor, the display, and the process control device.