To Bond or Not to Bond

An optically bonded display is so much better than a display with a standard cover glass touchscreen that there is really is no comparison. The display optics are not only dramatically improved but the touch performance is significantly enhanced. It is precisely why your mobile phone is optically bonded. It is easier to see in the sun, requires less backlight power, improves durability and makes the display stronger and lighter.

If you are looking for a high-performance, large format touchscreen display for your conference or training room, optical bonding is the only way to go.

What is optical bonding?

Optical Bonding 1aWith optical bonding, the cover glass of the touchscreen is directly adhered to the LCD display with a thin, uniform layer of adhesive, effectively eliminating the air gap between the cover glass and display. This process increases optical clarity, protects the display from dust and moisture, reduces parallax issues, and is thin and lightweight.

Optical bonding has been around for many years, but mainly used for small displays in specialty applications such a military, avionics, maritime and medical devices. This technology is now being utilized to enhance larger displays for its ability to improve optics and touch performance. Without bonding, the typical touchscreen assembly comprised of cover glass in front of the display causes distortions in the light path and a reduction of light. Optical Bonding 2This distortion can also affect your perception of where you are touching in which the display registers a touch point some distance away from the intended target. The issue has to do with parallax caused by the air gap between the cover glass and the front surface of the display. By filling that gap with an optical resin the internal refraction of light is minimized making for better optics and a more intuitive touch experience — specifically, your touch aligns with the display.

So why don’t you see optically bonded large format displays? Cost and complexity.

Optical Bonding 4The market for large format touch screens larger than 55” is still very small and so many prominent display brands do not have an off-the-shelf solution. For customers who want a large format touch display, OEMs work with regional integrators to make the necessary modification to their standard non-touch displays. However, since opening the display likely voids the warranty and may cause other issues, the most popular solution is a touchscreen overlay. An overlay is simply a touchscreen sensor placed in a custom bezel that wraps around the existing enclosure.

It works, it looks like the original display, but the experience of a touchscreen overlay for anything other than point-and-click applications is not optimal.

The problem is the gap between the front of the display and the touch screen which can be quite large depending on the depth of the stock bezel. And because of the assembly, optical bonding of an overlay is not an option.

Trends in the market.

Optical Bonding 3So. if you’re looking for a high-quality touchscreen display with brilliant visuals and a precise touchscreen experience, you may have to wait a bit. Companies such as Planar and Microsoft are starting to do their own bonding in the US. They are also using 4K displays which make for a superior viewing and interactive experience. So while the cost of displays and touch technology improves, more applications will utilize large format touch displays. Until the market increases sufficiently, optical bonding is likely to remain a novelty and be only available in very high end products.

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