What is a SAW touch screen and how does it work?

SAW technology: precision, clarity and durability for seamless interaction in public spaces.

Surface Acoustic Wave (SAW) touch screens are among the top 5 touch screen technologies. In this article, we delve into the intricacies of SAW touch screens and explain why they remain a quintessential choice for indoor environments where high level of human interaction is expected.

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What is a SAW (Surface Accoustic Wave) touch screen?

Surface acoustic wave (SAW) touch screens were developed mainly to address the drawbacks of low light transmittance in resistive film and capacitive touch panels. SAW technology is simply better for displaying detailed graphics and vivid colors. A SAW touch screen features a digital display interface that’s responsible for both creating images and supporting touch commands.

How does a SAW touch screen work?

Before going into the advantages of SAW touch screens, it's imperative to understand their fundamental workings. SAW touch screens operate on a principle involving the propagation of acoustic waves across the surface of the screen. Surface acoustic wave touch screens consist of one glass sheet with transmitting transducers, receiving transducers, and reflectors. When one touches the screen, it disrupts the ultrasonic waves, causing a decrease in their amplitude.When a user interacts with the screen, they disrupt these waves, enabling the device to precisely detect the touch point(s). This mechanism not only ensures remarkable accuracy but also facilitates swift response times, rendering SAW touch screens highly efficient in real-world scenarios.

Where can you find SAW touch screens?

Surface Acoustic Wave technology is recommended for any indoor or controlled environment with high traffic. SAW touch screens are often chosen for public information kiosks in settings like airports, train stations, museums, and shopping malls. They're also popular for interactive digital signage displays used in retail stores, hotels, restaurants, and other commercial settings. Their ability to withstand extreme temperatures, shock, and vibration make them suitable for use in aircraft, vehicles, and control systems in challenging environments. Other highly suitable applications for SAW touch screens include ATMs, ticketing kiosks, gaming machines, and computer-based training.

What sets SAW touch screens apart?

  • Impeccable clarity and durability. One of the most cited advantages of SAW touch screens is their unparalleled clarity and durability. Engineered with high-quality materials , these touchscreens boast exceptional optical clarity, thereby delivering an immersive visual experience to users. Since they rely on an outer layer made of glass, they don't require additional layers, such as overlays or coatings. This ensures minimal distortion, making SAW touch screens an ideal choice for environments where visual fidelity is highly important. 

The robust construction of SAW touch screens makes them capable of withstanding prolonged usage and environmental factors. This is due in part to the outer glass layer, which is inherently hardy and scratch-resistant. This durability not only translates to enhanced longevity but also reduces maintenance costs, making SAW touch screens a cost-effective solution for indoor public spaces.

  • Enhanced sensitivity and precision. SAW touch screens offer superior sensitivity and precision that enable seamless navigation and effortless interaction, catering to the diverse needs of users in public settings. They offer rapid response times, registering touch input almost instantaneously. Unlike resistive technology, the display only requires a light touch—there’s no need to exert any pressure to actuate the interface. Their higher sensitivity allows SAW touch displays to swiftly register commands, ensuring user interactions feel fluid and responsive, enhancing the overall user experience, and enabling applications that require real-time feedback, such as gaming and interactive displays.

SAW touch screens maintain a consistent and uniform response across the entire surface of the screen. This uniformity ensures that a touch input is detected with equal sensitivity and precision regardless of its location on the screen, eliminating issues such as dead zones or uneven responsiveness that can be found in other touch screen technologies.


What level of immunity to external factors does a SAW touch screen offer?

We already mentioned that the outer side of a SAW touch screen is made of glass that offers strong scratch resistance and almost no wear. The strength of the glass can be increased further using an ion exchange process, increasing the thickness of the glass, or even using two or three layers of glass. Moreover, SAW touch screens’ immunity to electromagnetic interference makes them an ideal choice for environments where electronic devices abound, mitigating the risk of interference and ensuring uninterrupted operation.

There is continuous advancement in SAW technology that makes it difficult to clearly answer if this technology is dust resistant. The way the screen is mounted, the use of specialty seals, and the size and placement of transducers can decrease the gap between the touch screen and the LCD—and even eliminate it in some configurations.  In general, anywhere there is grease or high amounts of dust, dirt, or water (such as near parking lots, in warehouses, or locations that are exposed to rain), SAW touch screens are not recommended. Direct sunlight, temperature extremes, prolonged exposure to high levels of humidity and moisture can interfere with the performance of SAW touch screens

Do SAW touch screens offer multi-touch?

SAW touch screens typically support only one touch with high accuracy—able to register touch locations down to fractions of a millimeter. Again, continuous advancements in technology are underway to enhance their multi-touch capabilities.

How do SAW touch screens compare in terms of price?

SAW touch screens generally fall into the mid-range to high-end price category among touch screen technologies. For example, resistive technology is cheaper, and advanced PCAP is more expensive. The cost is influenced by factors such as screen size, resolution, and customization options. The SAW technology and manufacturing processes contribute to their relatively higher cost compared to some other touch screen technologies.

The choice between SAW touch screens and alternative technologies depends on specific application requirements, budget considerations, and the desired balance between price, performance, and size. However, they have definitively proven that their durability and precision make them a top choice in demanding indoor environments with high activation. Contact NMG to let our engineers help you integrate SAW touch screens into your control and HMI products.

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