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Selecting the right touch screen to maximize results, Part 2

November 16, 2010 by Kurt Myrick — Technical Engineer, Phoenix Kiosk

Part 2 of 2

In my first blog about touch screens, I discussed basics and explained common touch screen sizes (including the benefits of having a large touch screen), as well as touch screen orientation (landscape vs. portrait).

In this blog, I’ll talk about the most common types of touch screen technologies, as well as what software considerations need to be taken into account with touch screens. Let’s delve right into it …

Common touch screen technologies – what are the different types?
There are many different types of touch screens, and it’s important for companies to choose the technology that will best suit their kiosk applications. Highlighted below are the three types of touch screens that are the most popular among our clients.

          Surface acoustic wave (SAW)
Surface Acoustic Wave technology is one of the most advanced touch screen types. It is based on sending acoustic waves across a clear glass panel with a series of transducers and reflectors. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point.

Because the panel is all glass there are no layers that can be worn, giving this technology the highest durability factor and also the highest clarity. This technology is recommended for public information kiosks, computer based training, or other high-traffic indoor environments.

We typically implement SAW technology for kiosks that have screens with sizes between 19 and 32 inches.

        Projected capacitive touch (PCT)
Capacitive sensors are used in devices such as laptop trackpads, MP3 players, computer monitors, and cell phones. Projected Capacitive Touch (PCT) technology permits more accurate and flexible operation by etching two separate, perpendicular layers of conductive material with parallel lines or tracks to form the grid (comparable to the pixel grid found in many LCD displays).

The PCT’s greater resolution allows operation without direct contact, so the conducting layers can be coated with insulating layers, and even operate under screen protectors, or behind weather and vandal-proof glass. The top layer of a PCT touch screen is glass, making the technology a more robust solution versus resistive touch technology. Depending on the implementation, an active or passive stylus can be used instead of, or in addition to, a finger. This is common with point-of-sale devices that require signature capture.

We typically implement PCT technology for kiosks that have screens 32 inches and larger, but the touch screens are available in smaller sizes.

         Infrared
An infrared touch screen uses an array of X-Y infrared LED and photo-detector pairs around the edges of the screen to detect a disruption in the pattern of LED beams. A major benefit of such a system is that it can detect essentially any input including a finger, gloved finger, stylus or pen. It is generally used in outdoor applications and point-of-sale systems which can't rely on a conductor (such as a bare finger) to activate the touch screen. Unlike capacitive touch screens, infrared touch screens do not require any patterning on the glass which increases durability and optical clarity of the overall system.

We typically implement infrared technology for kiosks that have screens with sizes 32 inches and larger.

What are the software considerations for touch screen kiosk deployment?
Some larger monitors may require a video card add-on if the onboard video chipset is not powerful enough to provide smooth video playback or does not support dual screen configuration. Other than this caveat with larger screens, you should not have to worry about any other software issues for touch screen deployment.

However, there is an important factor to keep in mind. As the LCD increases in size, your software user interface (UI) should be adjusted to the screen size/resolution that you are utilizing.

In other words, the buttons displayed on the screen may look large on a small screen, but they may look tiny on a larger screen with a higher resolution. This could make it difficult for the user to interact with your application via the touch screen. The UI layout needs to be created with a specific screen resolution in mind in order for it to be displayed properly.

Although some LCDs downscale or upscale graphics in order to fit them on the screen, this may still downgrade the quality of your application’s design, and therefore negatively affect the user interface.

Conclusion – consult with a professional to find the right touch screen
There are a number of touch screen technologies, and hopefully this overview of some of the most popular ones gave you a better understanding of those available. Even though this information may be helpful, it’s hard for the average buyer to determine what options might work best for their project. The best thing to do is consult with a well-established company that can help you find the right touch screen. 

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