A method and apparatus for determining a vertical and horizontal (X-Y)
target shot position on a Liquid Crystal or Plasma display screen may be
adapted to connect to commercially available video game console systems.
Upon a trigger event from a light gun when it is pointed at the target
shot position, a blanking signal renders the monitor black during a first
vertical refresh cycle. During a second vertical refresh cycle, the
voltage to each of the red, blue and green channels is increased in three
separate screen sections to create a display split between the three
colours. The light gun is adapted to be capable of separately detecting a
blue, red or green light pulse and the X-Y coordinates of the target shot
position is determined on the basis of the colour detected by the light
gun and the length of time which elapses between the start of the second
vertical refresh cycle and the detection of the red, blue or green light
pulse.