The easiest and most flexible user interface for a Liquid Crystal Display is a touch screen overlaying a Graphic LCD Module. This allows the designer to customize their interface specifically to their application, to allow dynamic adjustments to the user interface as the product ages, and to allow for alterations required for geographically different regions. Display Devices typically uses Analog-Resistive Touch Screens, and this approach gives use the following features:
- Proven Resistive Technology
- Simplicity of Interface Electronics
- Durable Plastic Construction
- Less Susceptible to Accidental Touch
- Ability to use Finger or Stylus to Activate Touch Screen
- High Linear Analog Output
Display Devices has integrated analog-resistive Touch Screen technology into displays as an standalone feature, where the customer will integrate their own decoder, or as a fully integrated assembly, where we have integrated the full decoding electronics. The next sections on this page will cover touch screen construction, operation, and application notes specifically set up for configurations used by Display Devices.
LCD Touch Screen Construction and Operation
The Analog-Resistive touch screens typically used by Display Devices are constructed of two layers of electrically conductive transparent films facing one another and separated by a gasket. Each layer has a set of parallel busbars positioned along the opposite edges and orthogonal to the busbars on the other layer. Busbars consist of screen-printed conductive ink terminated at the tail. The entire switch assembly is then mounted on a rigid Glass, Acrylic of Polycarbonate backer before it is attached to the front of our LCD Modules. Two opposing layers of Touch Screen are held apart by small separator dots until they come into contact by a light finger pressure. The voltage signal is then decoded by the controller to provide the application software with X and Y coordinates of the touch point.