MightyTrace
Technical details
The basis of the MightyTrace technology are liquid crystal displays (LCD) which
consist of some basic components like LC-matrix, diffusor, backlight and
reflector.
Since the LC-matrix, which displays the image, is transparent to infrared light, infrared signals can be seen by a sensor array behind the LC-matrix.
The sensors output an analog signal wihich represents the amount of infrared light "seen" by the sensors. This IR light is sent by interaction devices in front of the screen. By interpolation between the sensor values positions of the interaction devices can be computed.
The following image shows a cross-sectional view of the mighty trace setup.
The sensor array behind the screen has to be read out very fast in order to not disturb the users. A modular system is used.
- The ADC Boards convert the analog sensor values to digital ones.
- Slave Boards filter not active sensors.
- The Master Board collects all the active values from all the slaves and sends them to the computer.
In order to distinguish between all the different interaction devices which are used in front of the screen, the devices are activated serially. The activation speed is high enough (2000 Hz) to make sure the user does not perceive the serial interrogation behaviour.
Every device occupies 2 timeslots (frames). In the first frame the device just lights. The sensors can then interpolate the position. In the second frame the device can transmit its state.