In the TonerJet system toner particles move from a toner feeding roller through an array of holes (apertures) in a paper wide flexible printed circuit board to the print media. An electrical field between the toner feeding roller and the back electrode moves the charged particles. A number of electrodes in the circuit board modulate the electrical field, which makes the charged toner particles to either pass through the aperture or to stay on the feeding roller. A pair of deflection electrodes around each aperture makes it possible to deflect the toner particles from one aperture to three different dot positions.The movement of the charged toner particles has been simulated using two different simulation tools. In the first tool the electrical field is calculated with the software package ANSYS and the particle motion is calculated with the software package ADAMS. In the second tool both the electrical field and the particle motion are calculated in MATLAB.One aperture is simulated in either in 2D or 3D. The simulated particles are affected by electrical field forces, coulomb forces, mirror forces, collision forces, friction forces and air draught forces.