The four-layer anti-
reflective (4AR) touch panels, designed by Gunze Limited of Japan, are said to offer lower reflection without affecting the contrast of the screen. According to John Stetson, sales representative for Gunze’s U.S. division, this is a key feature for outdoor appliance applications. “This is more than just an engineering issue, it is critical to both engineers and end users,� Stetson says. “The benefit of an anti-reflective panel is reducing ambient light reflection, most importantly in direct-sunlight applications.�
To achieve the panel’s anti-reflective properties, layers of transparent, anti-reflective material are added to each horizontal surface on what Stetson refers to as a “touch-panel sandwich.� The layers consist of optical films coated with tin-doped indium oxide (ITO) materials such as SiO2 and TiO2. Thickness and layer number are designed to minimize the reflected lights.
According to Stetson, each layer of anti-reflective material increases the light output from the display. “This may sound counter-intuitive, but the reason that happens is that the anti-reflective material effectively reduces the optical interference with the display light,� he explains. “A single layer of anti-reflective film affects only a narrow range of visible light waves. Multiple layers of anti-reflective film prevent light reflection in a broad range of light waves.�
The 4AR touch panels, which are designed for both pen and finger input, feature a transmissivity rate of 88 percent. “Three-and four-layer anti-reflective films prevent light reflection and improve transparency rate,� Stetson notes. “This is important because end users demand panels that have high clarity and readability.�
The four layers also help make the panels more durable, which Stetson says was a top design priority. “In the past, there has been a trade-off, but as products evolve, this is no longer the case. Customers need both high transmissivity and durability,� he says.
Possible applications for the touch panels include consumer electronics and industrial equipment utilized outdoors. However, the anti-reflective technology can be applied anywhere a flat display is incorporated.