What is a touchscreen?
A touchscreen is a technology that allows a user to interact with a computer by touching the display screen without the use of a computer mouse. Touchscreens are used for a multitude of applications such as kiosks, digital signage, automation, transportation, and much more.
What is a capacitive (PCAP) touchscreen and how does it work?
There are two types of capacitive touchscreen technologies, surface capacitive and PCAP (projected capacitive). However, PCAP is the standard technology used for all capacitive touch screen applications. The construction of the PCAP touchscreen uses a top protective casing layer, usually made of insulating glass, then a transparent layer of electrode sensors that radiate an electromagnetic field that is sensing for conductivity, and finally a glass substrate. The electrode layer is made up of a checkered pattern of X electrodes and Y electrodes that change electrostatic capacity when a conductive object, in this case a finger, comes into contact. This reaction is relayed to a touch controller and pinpoints the location of contact and signals it to the computer.
PCAP Features
There are many features that make PCAP the standard touchscreen technology for industrial applications. The main benefit being multiple touch (multi-touch) point capabilities. Because of the architecture of PCAP, it can detect multi-touch points simultaneously (Also known as 10-point touch) which allows for gesture functionality. An example of a gesture is with the use of two fingers, users can zoom in/out on an application by using a pinching gesture. Additional key features are:
- Optical clarity and readability due to the transparent build of PCAP
- Accurate touch functionality
- Sensitivity recognition
- Liquid, contaminant, and scratch resistant since modern protective layers use tempered glass
- Premio’s optional ‘Optical Bonding’ fills the air gaps between layers with resin to enhance durability, clarity, readability, and vibrancy under bright environments
Drawbacks
- Prone to accidental inputs
- Limited to capacitive objects as input
- Expensive compared to resistive and surface capacitive touchscreens
What is a resistive touchscreen?
Resistive touchscreen technology relies on placing pressure to register a touch. This touchscreen is made up of a protective top film (usually made of clear polycarbonate), then a transparent electrode film made of ITO (indium tin oxide), spacer dots and insulators, another electrode film, and a glass bottom layer. The mechanism is very simple, when an object puts pressure on the screen, the space between the two transparent electrode films comes into contact and produces voltage change. This signals the touch controller the coordinates of the contact and registers it to the computer.
What are the most popular resistive touch technologies for Industrial Applications?
There are two main commonly used resistive touch technologies, analog 4-wire and analog 5-wire resistive touch. 4-wire resistive touchscreen uses the traditional method of using both electrode film layers to triangulate the location of the touch point. This touchscreen is the most cost-efficient, due to its simplistic design for low-end applications. 5-wire resistive touchscreens are the staple for industrial applications because of their longevity, reliability, and ruggedness. Analog 5-wire resistive touchscreens only use the bottom electrode layer instead of both like 4-wire. Because the top film only serves as a protective layer between the contact object and electrode film, the top film can endure long-term abrasion without hindering touch performance and accuracy. Additionally, there is an increased touch sensitivity, so users do not need to put much pressure on the display to register while still having a zero tolerance to accidental inputs.
Resistive Touch Features
While PCAP touchscreen consists of nearly 90% of the touchscreen market, resistive touchscreen technology remains extremely relevant in the industrial sector. Because it only detects one point of contact and requires pressure rather than a simple touch to register, it has zero tolerance for errors and accidental inputs are eliminated. Other essential features are:
- Cost effective because of design simplicity
- Power efficient with the least amount of electricity consumption compared to other touchscreen technologies
- Liquid and contaminant resistant
- Registers with gloves, stylus, etc. because it does not require a conductive object like PCAP touchscreens, pressure onto the screen is all that is needed.
- High response rate, resistive touchscreen is known for their rapid response times
Drawbacks
- Reduced image quality due to multiple films layered onto the screen
- Impermanent protective film, with more usage, the film begins to fatigue
- Periodic recalibration due to analog drift
- Limitations to screen size (reduced detection accuracy with larger screen sizes and can be prevented by combining multiple screens)
Choosing the right touch technology
There are various factors that come to equation when deciding between a capacitive or resistive touchscreen. Some guiding advice is to help you find out which touchscreen technology is best for you.
Purpose: What will you be using it for? Do you need to use multi-touch?
There is a lot of functionality that PCAP touchscreens offer, however, resistive touchscreens can perform better with less features. Sometimes less is more.
Registering Inputs: Will you be wearing gloves, using a stylus, or bare fingers? Is there lenience on accidental inputs?
PCAP touchscreens have zero tolerance for accidental inputs due to the pressure needed to register an input and can be used with gloves or stylus. PCAP requires a conductive object like a finger or specialized stylus.
Display clarity: Will you be operating in a high brightness room or outdoors?
PCAP touchscreens have better image clarity and readability that allow for less glare in bright conditions.
PCAP touchscreens use tempered glass as an outer protective layer while resistive touchscreens use a protective film that will degrade over a long period of time.
Side by side comparison – PCAP vs Resistive
| Features | PCAP | Resistive |
| Multi-touch | Yes | Single-touch only |
| Touch sensitivity | High (Customizable) | Low |
| Touch Material | Fingers or specialized stylus | Any |
| Optical clarity & readability | Excellent | Good |
| Size compatibility | Any | Limited |
| Maintenance | None | Occasional recalibrations |
| Power Efficient | Good | Excellent |
| Rugged | Yes (Optional optical bonding) | No |
| Cost | $$$ | $ |
Industrial Touchscreen Panel PCs & Touch Monitors
VIO
Premio’s all-in-one VIO series is an IP65 fanless Industrial Touchscreen Panel PC and Monitor with configurable PCAP or 5-wire Resistive touchscreen technologies. The VIO is designed for HMI automation, communication, and information applications with a rugged architecture to remain operatable in harsh industrial environments. Optionally, Premio offers Optical Bonding technology for improved durability and High-Brightness Panels for enhanced display visibility.
SIO
Built with a stainless-steel enclosure for corrosion resistance, Premio’s SIO series is an IP66/IP69K rugged fanless Washdown Touchscreen Computer for cleanrooms and aseptic industrial environments. The SIO is constructed with a 7H hardness display glass, low profile cableless and fanless design, and built to withstand high-pressure and high-temperature washdowns. Like the VIO, Premio’s SIO is offered in both multi-touch PCAP and single-touch 5-wire resistive touchscreen technology, along with customizable display screen sizes and optional Optical Bonding technology and High-Brightness Panels.
WIO
The WIO series is Premio’s IP66 Waterproof Touchscreen Computer with PCAP touch technology. Configurable with wireless connectivity, Optical Bonding, and hardware components, the WIO is essential for heavy industrial applications where liquid, debris, and corrosive elements can affect the performance of hardware. Built rugged and with a stainless steel enclosure, Premio’s WIO is capable of operating in the harshest of industrial environments.
Additional Touchscreen Technologies
Surface capacitive Touchscreens
Constructed like PCAP, however limited to single touch. Being made up of a single transparent electrode film between a glass substrate at the bottom and protective cover on top, surface capacitive touchscreens have a uniform electromagnetic field that seek for voltage decreases on any point of the screen and relays that signal to a controller. Because of this architecture, surface capacitive can only detect one touch at any given time. Premio does not use surface capacitive touchscreens due to its unsustainability in harsh environments.
Surface Wave Acoustics (SAW) Touchscreens
SAW touchscreens are a type of resistive touch technology but use ultrasound waves to register inputs. It was used to improve the optical clarity and brightness that resistive touchscreens lacked by replacing layers of film with glass. Between a pair of glass panes, are two transducers and receivers on opposite sides of each display corner, and sound wave reflectors installed around the perimeter of the encasing. Touch from an object is detected when ultrasound waves are interrupted and coordinated through a touch controller. SAW touchscreens are durable, scratch resistant with its glass construction, and have improved optical clarity while remaining pressure based. As much of an upgrade from resistive touchscreen it may seem, SAW still requires occasional calibration, is not resistant to contaminants and liquids, and lacks sensor longevity. Premio provides touchscreens that need to be rugged and reliable with little maintenance.