PCAP vs. Resistive Touch on the Factory Floor: Why Advancements in PCAP Technology Are Replacing Resistive as the Go-To for Industrial Applications
Selecting touchscreens for the factory floor can be tricky when it comes to compatibility with thick gloves and environmental concerns. In fact, for many years, resistive touch technology has been the first choice for most touchscreen controls found on industrial machinery. Resistive touchscreens are reliable and responsive to bare or gloved hands. While Projected Capacitive (PCAP) touch offers improved optical clarity and scratch resistance, it has historically not performed well with gloved hands. However, new advancements in PCAP are changing that and making it a viable solution for industrial applications. Below we explain how and why the new PCAP technology is replacing resistive as the go-to for industrial applications.
Resistive Touch Technology
Industrial controls traditionally employ resistive touchscreens. This technology features two transparent layers separated by a thin gap with spacers. Each layer internal side has a conductive coating. As a result, the touch point is activated when the two layers are pressed against each other which triggers a voltage to pass through. Resistive Touch technology works thanks to pressure, and it is immune to the electrical property of capacitance (in contrast to capacitive touch). This means that the technology will identify a touch with a finger or an object. However, the surface of the touch sensor is invulnerable to foreign objects such as dust and waterdrops (in contrast to the technologies employing the principles of wavelength, i.e. IR and SAW touch). Nevertheless, Resistive touch includes several disadvantages:
- Usually supports only a single touch
- Lacks optical clarity
- Susceptible to scratches from tools
- Can wear out overtime on an overused spot
- Not available beyond 24” size due to economic scale
Projected Capacitive (PCAP) Touch Technology
Projected Capacitive touch technology (PCAP) is a variant of surface capacitance touch (or traditional capacitive touch), and it was first adapted by the consumer/ commercial market in the early 2000’s. Compared to the traditional capacitive touch technology, PCAP touch offers many improved features and quickly gains popularity as the touch technology of choice by most of the end users. PCAP touch differentiates itself by offering, for most applications, dual touch, rotation, zoom, flip, and multi-touch of up to 10 fingers. By changing the principle from surface capacitance to projected capacitance, this technology enables a touch point by a finger, with or without thin gloves, and passive stylus sensing to be projected accurately and reliably through layers of glasses.
PCAP Touch quickly won over the market share from resistive touch in applications where customers require a more rugged surface due to susceptibility to scratches and mishandlings, such as in ATMs, retail, and Kiosks. Because of its optical clarity compared to resistive touch, PCAP also started to win over many medical applications.
Recent Improvements in PCAP Technology
Below we discussed some features that allow this technology to overcome the challenges of the past.
1. Touch Controller
There are two options for incorporating touch controllers in the PCAP touch devices. In the first one, an Integrated Circuit (IC) controller is mounted on the surface on a separate PC board, known as Chip on Board (COB), which allows signals to be transmitted from the touch sensor through the flexible printed circuit to the PCB. Then, the IC firmware will transform the capacitance data into a digital touch position data which will be sent to the host computer.
The second option is to mount the controller IC chip on the surface directly on the touch flex tail, also known as Chip on Flex (COF). In this case, an analog capacitance signal is converted into digital position data on the FPC which will be sent to the computer via serial interface.
2. Noise Immunity
Electromagnetic interference (EMI) noise can interfere with the accurate detection of touch events in PCAP touchscreens. To maintain the accuracy of the touch detection, the PCAP touch controller leverages firmware and hardware to avoid noise interference at different frequency bandwidths.
3. Water Handling
On certain industrial applications, water can accumulate on top of PCAP touchscreens and trigger false touches. To avoid those false touches, the latest PCAP technology features water repellant surface treatments and a firmware algorithm to differentiate an actual touch from water droplets. These new features enable the touch screens to work flawlessly with challenging operating conditions.
4. Gloved Touch
The improved algorithm on PCAP touch controller firmware enables the touchscreen manufacturer to be able to tune the projection field for different applications, thus enabling workers to keep their thick working or safety gloves while operating on their HMI equipment.
5. Thick Cover Lens
To improve precision, certain PCAP touchscreens now include a thicker glass which will detect fewer signals while increasing the signal strength and maintain an optimal noise ration.
Although the Resistive touchscreens have been the go-to for industrial applications for many years, the latest PCAP touch technology has overcome the challenges presented by thick gloves and rough operating conditions. The breakthroughs in IC controllers, drivers and firmware further improve performance, increase precision, and reduce EMI noise.
As a result, you can leverage PCAP touch technology for better durability, improved scratch resistance, and greater touch precision for your industrial applications.
Contec has been providing purpose-built display technology solutions for industrial and medical applications for over 40 years. In 2020, Contec launched two new lines of rugged Panel PCs.These modular “all-in-one” systems that combine a high performance, energy-efficient computer with advanced touch screen display technology. Additional features like shock and vibration resistance, sealed front bezel, and industry-leading display brightness, make the PT-S2000 and PT-S959 series well suited for industrial automation, machine control/HMI, transportation, metal extrusion, CNC machining, and other industrial uses. In early 2019, Contec debuted a new, US-based clean room facility for custom display integration and OEM kits.
If you have any questions about the recent advancements in PCAP touch technology or its uses, please contact us to speak with an expert.