Types of Interactive Technologies

Ultrasonic and Infrared When pressed to the whiteboard surface, the marker or stylus sends out both an ultrasonic sound and an infrared light. Two ultrasonic microphones receive the sound and measure the difference in the sound's arrival time, and triangulate the location of the marker or stylus. This technology allows whiteboards to be made of any material, but requires an active dry-erase marker or stylus. Analog-resistive Two electrically conductive sheets are separated by a small layer of acetone. When they touch, the surface sheet is deformed, and electrical contact is made. The resistance changes in the sheets establish the (X,Y) location of the touch. This technology has a soft writing surface and allows one to use a finger, a dry-erase marker, or a stylus on the whiteboard. In other words, when you push against the board using a special pen or your finger, two resistive sheets contact thereby creating an electrical signal and passing that to the computer. Electromagnetic An array of wires behind the board interacts with a coil in the stylus tip to determine the (X,Y) coordinate of the stylus. Styli are either active (require a battery or wire back to the whiteboard) or passive (alter electrical signals produced by the board, but contain no power source). This technology usually has a hard writing surface with no moving parts. Advantages of electromagnetic mode include increased robustness, the fact that the electronic stylus can be naturally rested on the whiteboard when writing, and a very high level of accuracy. In other words, there are magnetic sensors in the board that react and send a message back to the computer when they are activated by a magnetic pen. Laser An infrared laser is located in each upper corner of the whiteboard. The laser beam sweeps across the whiteboard surface—much like a lighthouse sweeps light across the ocean—by using a rotating mirror. Reflectors on the stylus or marker reflect the laser beam back to the source and the (X,Y) position can be triangulated. This technology has a hard (usually ceramic on steel) surface, which has the longest life and erases most cleanly. Markers and styli are passive, but must have reflective tape to work. Touch cannot be used. Optical and Infrared When pressed to the whiteboard surface, the finger or marker sees the infrared light. Software then manipulates the information to triangulate the location of the marker or stylus. This technology allows whiteboards to be made of any material; with this system no dry-erase marker or stylus is needed. Interactive whiteboards are available in two forms: Front Projection and Rear Projection. Front Projection Whiteboards - have a video projector in front of the whiteboard. The only disadvantage to these boards is that if the presenter must stand in front of the screen and their body will cast a shadow. Presenters quickly learn to compensate for the shadow by slightly extending their arm with or without a stylus. Additionally, recent innovations in Short Throw Projection systems from the major manufacturers vastly reduce the shadow effect. Many manufactures now provide an option to raise and lower the display to accommodate users of different heights. An active wand is also available to provide a pointing and writing device combined into one. Rear Projection Whiteboards - projectors are located behind the whiteboard so that no shadows occur. Rear projection whiteboards are also advantageous because the presenter does not have to look into the projector light while speaking to the audience. The disadvantage to these systems are that they are generally more expensive than front projection whiteboards, are often large, and cannot be mounted flush on a wall; however, "in-wall" installations are possible. Flat Panel Overlays for Interactive Displays/Whiteboards Overlays can be used to convert plasma and liquid crystal display (LCD) flat panels into interactive displays/whiteboards. All interactive whiteboard functionalities can be reproduced with flat panel overlays including on-screen drawing, screen capture, image display, software application interaction and video playback. Like rear projection interactive whiteboards, there is no problem with shadows cast by the presenter. The slim profile of widescreen displays offers convenient installation options such as wall mounting.