Temperature changes, especially when occurring quickly, pose a unique challenge to projected capacitive (PCAP) touch products.  PenMount firmware has a proprietary feature to stabilize the touch signal whether there is an environmental change or temperature change.  This feature is System Reference (SR).  Different materials undergo small physical changes depending on material and changing temperatures.   When temperature changes by 1 degree Celsius, materials will be accordingly expand or contract.  Objects tend to expand when heated and contract when cooled and different materials will exhibit different rates of expansion and contraction due to different thermal expansion coefficients.  These physical phenomenon cause changes in the volume and area of materials, PCAP design pattern, and the PCAP touch panel itself.  Of course, this will then change the signal obtained by the controller.

When PCAP touch operation is initiated, the controller collects background data.  This background data is constantly fluctuating so the controller must continuously collect this data to understand the environment of user’s application.  When a touch or noise interference occurs, this will be represented in raw data.  The disparity of raw data and background data signal is used by the controller to determine whether the signal originates from a touch or noise.  When temperature rises or falls, raw data will rise and fall.  When a discrepancy occurs, controller firmware must immediately update background data.  Otherwise, the touch signal will be erroneous when temperature changes.

PenMount’s SR technology comprehensively processes the values obtained by firmware and compares the results to trending disparities in background data.  This compensates for abnormal PCAP signals caused by temperature changes and allows PCAP panels paired with PenMount firmware to operate in the temperature range of -40°C to 85°C.

Some projects require no impact from rapid temperature changes on operation such as trains running in cold climates.  When the train is running, temperature is relatively high but falls rapidly when the train stops or is in storage.  A heater is often attached in front of the LCD and behind the touch panel.  Once the train starts again and the heater initiates, the touch panel controller must quickly detect the temperature change to process the touch signal to reflect the true touch position.  This technology is also useful for devices moving to and from industrial freezers or other environments with large temperature transitions.

PenMount is your best PCAP touch controller, to find out more about PenMount’s environmental solutions, please contact our sales representatives.

You are welcomed to download all of PenMount’s standard product data and drivers directly from our website at: //www.salt.com.tw and //www.PenMount.com.

If you have any suggestions or comments please send e-mail to: salt@salt.com.tw .