To understand clearly how the interactive white boards might be able to improve the teaching environment, you need to understand the sensing technologies which are used to track the interaction on the screen surface. These are resistive, laser, infrared optical, camera based optical and ultra sonic. Among all these technologies, the most successful in commercial interactive whiteboards use electromagnetic and resistive technology.
The resistive touch screens are made up of two flexible sheets each with a coat of resistive material and separated by a layer of micro thin air space. In operation the two screens press together, hence registering the exact location where the screen was touched. With this technology one can use a finger, stylus or any other pointing device. With the electromagnetic technology the board features an array of wires embedded under the board surface. These interact with the stylus tip to give the exact location using the X and Y coordinates.
The type of stylus varies. You can use an active stylus which uses battery power or which is wired to the white board. There are also passive styli which rely on electrical signals produced by the white board hence requiring no external source of power. In simple terms the electromagnetic white board can be described as having magnetic sensors which react and send messages to the computer when the board is activated by use of a magnetic pen.
Apart from the two major technologies, the other technologies are also gaining momentum in the interactive white board market and therefore should not be ignored. With the optical infrared technology, you need to press the board surface for the infrared light to be visible. This allows the support software to triangulate the location of the stylus or marker. With this technology, the whiteboard can be made from any material.
The laser interactive whiteboard technology uses an infrared laser located in the upper corners of the whiteboard. The laser beams operate by sweeping across the surface of the whiteboard using rotating mirrors. The marker or stylus used to write on the board reflects the laser beams back to the source hence enabling the triangulation of the X and Y coordinates. This technology works well with a hard surface such are steel or ceramic which also have the advantage of easy cleaning.
With ultrasonic and infrared, the stylus sends out an ultrasonic sound as well as infrared light when pressed on the board surface. The board has two ultrasonic microphones that receive the sound and calculate the differences in arrival time. This helps in the triangulation of X and Y coordinates. This technology also allows the whiteboard to be made from any material. However, a suitable adapted stylus or active dry-eraser marker is necessary.
Apart from these technologies there are also other less significant technologies such as frustrated internal reflection, ultrasonic only and Wii Remote IWB. Although interactive whiteboards are technologically advanced, there are certain issues which are common with most types. For instance using permanent markers on the whiteboards can cause problems. Another common issue is the risk of dents, punctures and other damages to the surface which are not experienced with normal boards.