Benchmarking - Touch Screen Options
The Main Components of Touch Screen
Every touch screen has three main components:
- Touch Sensitive Surface
The touch sensitive surface is an extremely durable and flexible glass or polymer touch response surface, and this panel is placed over the viewable area of the screen. In most sensors there is an electric signal going across the screen, and a touch on the surface causes change in the signal depending on the touch sensor technology used.This change allows the controller to identify the location of the touch.
- The Controller
The controller is a device that acts as the intermediate between the screen and the computer. It interprets the electrical signal of the touch event to digital signal that computer can understand. The controller can be placed with the screen or housed externally.
- The Software Driver
The software driver is an interpreter that converts what signal comes from the controller to information that the operating system can understand.
Popular Touch Screen Sensor Technologies
Resistive Touch Screens
A resistive touchscreen panel is composed of several layers, the most important of which are two thin, metallic, electrically conductive layers separated by a narrow gap. When an object, such as a finger, presses down on a point on the panel's outer surface the two metallic layers become connected at that point: the panel then behaves as a pair of voltage dividers with connected outputs. This causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. Resistive Touch Screens are durable and resistant to humidity and liquid spills. But they offer limited clarity, and the surface can be easily damaged by sharp objects.
Capacitive Touch Screens
In these devices a glass panel with a coat of charge stores material on its surface. When the panel is touched, a small amount of charge is drawn at the point of contact. Circuit located at each corner of the screen measure the difference in charge and send information to the controller for calculating the position of touch.These are used where the clarity precision is of concern as in laptops and medical imaging.
Surface Acoustic wave Touch Screens
This technology uses ultrasonic waves that pass over the screen. When the panel is touched, there is a change in the frequency of ultrasonic wave and the receiver at end of the panel registers this change.Since only glass is used with no coating, there is nothing that wears out.
Infrared Touch Screens
Infrared touch screens are primarily used for large displays, banking machines, and in military applications. Infrared touch screens are based on light-beam interruption technology. Instead of an overlay on the surface, a frame surrounds the display. The frame has light sources, or light emitting diodes (LEDs) on one side and light detectors on the opposite side, creating an optical grid across the screen.When an object touches the screen, the invisible light beam is interrupted, causing a drop in the signal received by the photo sensors.
Others
- Optical Touch Screen http://en.wikipedia.org/wiki/Touchscreen
- Dispersive Signal Technology
- Strain Gauge
- Microsoft's Surface Tchnology http://www.microsoft.com/surface/
Touch Screen Technology Comparison
- Touch Screen Technology Comparison10-01-30_Touch Screen Technology Comparison.pdf
Touch Screen Technology for Kiosk
- 3M Innovation: MicroTouch Capacitive Touch Screen http://www.3m.com/us/electronics_mfg/Touch_Systems/downloads/PDFs/Capacitive-OV.pdf
- Elo Touchsystems: IntelliTouch Surface Wave Touchscreen http://www.elotouch.com/Products/Touchscreens/IntelliTouch/default.asp
- IBM: IBM AnyPlace Kiosk http://www-03.ibm.com/products/retail/products/self/anyplace/index.html
Documents
- Introduction to Touch Screen Whitepaper10-01-30_Introduction to Touch Screen Whitepaper.pdf
- Apple's Proposed Multi-touch User Interface System http://www.lukew.com/ff/entry.asp?983
- Touch Design Guidelines(Microsoft) http://msdn.microsoft.com/en-us/library/cc872774.aspx
Companies
- Nortd Labs http://labs.nortd.com/touchkit/
- Elo TouchSystems http://www.elotouch.com/Products/Touchscreens/default.asp