Resistive Touch Screen Technology
Resistive touch screen technology consists of a glass or acrylic panel that is coated with electrically conductive and resistive layers. The thin layers are separated by invisible separator dots. When operating, an electrical current moves through the screen. When pressure is applied to the screen the layers are pressed together, causing a change in the electrical current and a touch is registered.
Although clarity is less than with other touch screen types, resistive screens can be highly accurate and have the advantage of being pressure sensitive so it responds to any input device, including finger, gloved hand, or pen stylus
Resistive touch screen technology is the most cost effective technology on the market today. It is recommended when budgets do not allow more robust solutions.
Limitations of resistive touch screen technology:
• Can be relatively easily damaged by scratching
• Can be relatively easily damaged by poking
• Can be relatively easily damaged by impact
• Not recommended for public access applications
• Requires periodic recalibration
• Can wear through regular use over time
Capacitive Touch Screen Technology
Capacitive touch screen technology is a popular and durable technology that is used in a wide range of applications. It has a higher clarity than resistive technology, but it only responds to finger contact and will not work with a gloved hand or pen stylus. A capacitive touch screen consists of a glass panel with a capacitive (charge storing) material coating its surface. Circuits located at corners of the screen measure the capacitance of a person touching the overlay.
Capacitive touch screen technology is often recommended to customers who would like the confidence of a brand name LCD such as NEC, which the capacitive touch screen would then be retrofitted to.
Limitations of capacitive touch screen technology:
• Can not be used with a gloved hand
• Can not be used with stylus
• Requires periodic recalibration
• Often retrofitted to standard non-touch LCD monitors which may not be as stable when touched
• Not usually fitted to monitors when applications require dust, water, scratch or impact resistance
SAW Touch Screen Technology
Surface Acoustic Wave (SAW) touch screen technology is based on sending acoustic waves across a clear glass panel with a series of transducers and reflectors. When a finger touches the screen, the waves are absorbed, causing a touch event to be detected at that point.
Like infrared technology, the panel is all glass, so there are no layers that can be worn, or damaged over time. This makes SAW touch screen technology highly durable and suitable for applications where high clarity is desired.
SAW touch screen technology is recommended for public information kiosks and other high traffic indoor environments.
Limitations of SAW Touch Screen Technology
• Must be touched by finger, gloved hand, or soft-tip stylus. Something hard like a pen, credit card or finger nail won’t work
• Can be affected by large amounts of dirt, dust, and / or water in the environment.
• Relatively expensive in comparison to other technologies
Infrared touch screen technology
Infrared technology uses a small frame around the display with LED’s and photo receptors hidden behind an infrared transparent bezel. The controller pulses the LED’s to create a grid of IR light beams. A touch obstructs the beams which identifies the X and Y coordinates.
Benefits of infrared technology:
• Can be scaled to any size without losing resolution
• Calibration stability – no touch point drift
• High clarity and light transmission
• High chemical, scratch, breakage, and liquid resistance
• High sealability from dust and liquids
• Touch can be activated by anything including finger, gloved hand, or stylus
• High durability since a touch is only interrupting light beams