The basis of the MightyTrace technology are liquid crystal displays
(LCD) which consist of some basic components like LC-matrix, diffusor,
backlight and reflector.
Standard LCD
components
The
Sensor Array
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 modified LCD
setup with an infrared sensor array
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
Sensor
Readout
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.
The sensor read
out electronics behind the LCD components.
Device
Identification
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.
Liquid
Crystal Displays
