Abstract: The present invention discloses methods and systems for continuously repositioning a shading element to shade an eyepoint from the direct rays originated from a source of radiation. Different ways to simplify the methods are presented, including the use of a repositioning means which continuously repositions the shading element to shade a target location from the direct rays. Also suggested are novel devices to serve as the repositioning means, which may be incorporated in the systems. In embodiments as a visor system on transportation vehicles, this invention avoids a number of shortcomings and limitations of prior systems. It provides practical solutions to the dual problem with conventional visors: their size were too big and too small. This invention enables the vehicle occupants to have a more open field of view while the eyes are always protected from direct sunglare, making it safer and more pleasant to travel.

Abstract: A two dimensional matrix of liquid crystal cells is laid on the surface of a vehicle's windshield. The sunshade is formed by selectively turning some of the cells to be less transparent. The size of the sunshade is close to the minimum necessary to cast an umbra covering the vehicle occupant's eyes. A three dimensional Cartesian coordinate system is used, in which the z axis is parallel to the direction of travel and perpendicular to the x and y axes. The coordinates of an internal target are stored in the memory and may separately be increased or decreased by pushing some buttons. In a normal mode of operation, the microprocessor continuously repositions the sunshade to shade the target from direct sunlight. The computation is based on the image of the sun captured by a two dimensional CCD, the relative locations of the CCD and the optical center of a lens forming the image on the CCD, and the locations of the target and the windshield surface.