The parts of the flight plan of an aircraft corresponding to lateral trajectories at low altitude can comprise passages with limited lateral freedom of deployment because of risks of collision with the ground, or because of obstacles on the ground. An outer wall of the inner pipe has thereon a ridge portion, which defines a groove portion extending in a longitudinal direction of the inner pipe. A pair of switches may be mounted in separate locations to detect the position of a control arm used to rotate the trunnion arm. When the scan signals are applied to the scan lines, voltage swings of the pixel capacitors charged by image data on data lines decrease, rapidly charging the pixels.