Optical Bonding

Optical Bonding and PCAP: A very effective combination

In most designs there is an air gap between the display and the touch screen. This air gap gives problems with readability in certain conditions. The solution for this is optical bonding from Danielson. Optical bonding is the use of an optical-grade adhesive to glue a touch sensor to the top surface of a display. Optical bonding eliminates the air gap between the cover glass and the display. Moreover, anti-reflective coating is often used in optical bonding glass.

The real problem for display readability in outdoor environments is not the display’s brightness but its contrast. Contrast means the ratio of the white level to the black level; in other words, the contrast ratio of display means the difference of light intensity between the brightness white pixel and the darkest black pixel. The main purpose of optical bonding is to increase the display’s contrast ratio by reducing the amount of reflected ambient light. 

Benefits of Optical Bonding

1. Increased ruggedness: Bonding a touch sensor on top of the display increases the ruggedness of the display.
2. Improved durability: A bonded display is better able to resist scratches, fluids, stains and dirt.
3. Condensation: The elimination of an air gap between the cover glass and the display means that moisture cannot penetrate and cause fogging on display’s surface.
4. Clarity & Viewability: Optical bonding eliminates the internal reflection between the LCD and the cover glass or touchscreen because the bonding process creates a single index of refraction. Reducing internally reflected light loss increases display contrast and viewability.
5. Improved heat dissipation.