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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. In a special mode of operation, the microprocessor continuously repositions the sunshade to a position having the same x,y-coordinates as the target. With this sunshade system, the method comprises the steps of (a) switching the system to the special mode and adjusting the x,y-coordinates of the target until the sunshade is repositioned straight ahead of, and at the same height as, the eyes; and (b) switching the system to the normal mode and adjusting the z-coordinate of the target until the sunshade shades the eyes from direct sunlight. Thus the target is coincident with the eyes, and the system will always reposition the sunshade to shade the eyes from direct sunlight.

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First Claim