PCAP and AR Touchscreens in a Rugged Environment
This document will highlight the differences and similarities between a Projected Capacitive touchscreen and an Analog Resistive touchscreen for a rugged environment. First, we will review the definition of each touchscreen technology.
Projected Capacitive (PCAP)
Projected Capacitive touchscreens have a transparent conductive coating of sensors. The sensors, when touched by other capacitive bodies (i.e. finger or stylus) can sense the conductive properties of the touching object and record a touch event.
Analog Resistive (AR)
Analog Resistive touchscreens have two transparent layers separated by a thin gap. The internal side of each layer has a conductive coating. When the two layers are pressed against each other this allows a voltage to pass through which then records a touch event.
PCAP touch works with electrical capacitance whereas AR touch works utilizing pressure. If you own a smartphone, then you have also owned and used a PCAP touchscreen. Each touchscreen type (PCAP, AR) can be useful in rugged environments. To help you better understand which touchscreen to choose for your application, we have created the below overview and summary chart.
General Overview of PCAP and AR for Ruggedization
- A PCAP touchscreen can support up to 10 simultaneous touches, and gesturing such as pinch, scroll, rotation, zoom, and flip, providing excellent responsivity for multi-touch.
- An Analog Resistive touchscreen typically supports a single touch. However, some AR touchscreens can support multi-touch.
- Environment Conditions
- PCAP touchscreens have a strong, chemically strengthened glass (gorilla glass) layer for protection. With a pencil hardness of 9H, PCAP is highly scratch-resistant. The PCAP touchscreen can still be used even after being cracked or damaged. For example, you have probably seen someone use their smartphone with a cracked screen.
- AR touchscreen’s upper sensor layer is plastic; however, the AR plastic layer can be protected by a glass layer for additional rugged properties.
- PCAP touchscreens provide excellent sunlight readability.
- AR touchscreens have a thin gap between the layers that is filled with air or with an optically clear adhesive. These extra surfaces/layers, even with optically clear adhesive, can result in reduced light output due to reflectance on each surface.
- AR touchscreens can “yellow” or haze over the lifetime of the product and affect the readability of the display.
- PCAP and AR touchscreens will work with fingers, gloves, or stylus.
- Gloves and stylus must have capacitive properties to work on PCAP touchscreens. PCAP touchscreens may need to be calibrated for the size of the touch area if the use case involves different size gloves/stylus (e.g., thick vs. thin gloves).
- On AR, the finger, glove, or stylus must be pushed down to initiate the touch event.
- AR touchscreens and PCAP touchscreens (when properly calibrated) work well in dusty, humid, or moist conditions.
- Electro-Magnetic Conditions
- AR touchscreens are low risk for EMI concerns.
- PCAP touchscreens can be protected against EMI. It is possible to protect PCAP touchscreens (via the touchscreen controller) to meet MIL-STD-461F for radiated emissions and electromagnetic compatibility; and MIL-STE-1275E for electrostatic discharge.
- PCAP and AR touchscreens are similar in cost.
|Great - Up to 10
|Good - Up to 2
|Good – requires capacitive object
|Great – any object
|Great - Up to 9H hardness
|Good – Up to 7H hardness
|Good – can degrade over time
|Good – can be calibrated for best (Great) performance
The below table lists the qualification tests that have been performed and qualified on ArgonFDS display products with PCAP and AR touchscreens.
|CS 101, Audio Freq CS
|Induced Signal Susceptibility
|Ground Survival High Temperature
|Emission of RF Energy, Radiated
|Operating High Temperature
|Emission of RF Energy, Conducted
|Operating Low Temperature
|Lightning Induced Transient Susceptibility
|Ground Survival Low Temperature
|Short Time Operating Low Temperature
|Short Time Operating High Temperature
|CS 101, Audio Freq CS
|Sand and Dust
|Shock and Operational Safety
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