Optical bonding is a method to improve the image display and longevity of monitors. During this process, the air gap between the LCD module and the protective screen or the touch surface, which occurs with conventional touch screens, is filled with a highly transparent liquid adhesive.
Bonded displays offer various advantages over conventional touch screens. By filling the air gap with a mass adapted to the refractive index, it is possible to avoid internal (reverse) reflections and allow more light to pass from the LCD panel to the user (increase transmission). In addition, reflections from external light sources are minimized, since the absence of interfaces (e. g. from air to glass) reduces the scattering loss/reflected component. This is particularly evident in the increase in brightness (approx. 3.. 5%) and contrast (25... 50%) compared to non-bonded displays. A desired side-effect of optical bonding is the more precise operability of the touch screen by minimizing the parallax error, which is especially important for lateral viewing.
The additional layer (synthetic resin or similar) also increases resistance to mechanical influences and thus increases the service life of the display in harsh environments.