Abstract: This invention presents a projection-receiving surface that has a surface having an undulating contour. The undulating contour comprises a plurality of alternating convex cylindrical surface segments and concave cylindrical surface segments. The convex cylindrical surface segments and concave cylindrical surface segments of the undulating contour of the surface arranged with cylindrical axes in a direction. The surface can further have an additional surface feature comprising striations, cusps, and/or nanoflaked reflector leaves. The striations are arranged crosswise to the undulating contour. The surface can be a reflection surface of a front projection-receiving surface.

Abstract: A spa cover lifter for moving a spa cover from a closed position to a storage position includes a drive mechanism, a fixed base and a lifting arm assembly. The lifting arm assembly is mounted to first or second leaves of the spa cover. The lifting arm assembly is driven by the drive mechanism and is moveably mounted to the fixed base. The lifting arm assembly includes a cover pivoting assembly and a cover transporting assembly. The cover pivoting assembly is driven by the drive mechanism to move the cover from the closed position to an intermediate position and the cover transporting assembly is driven by the drive mechanism to the move the cover from the intermediate position to the storage position. The spa cover lifter has an automatic shutoff for cutting power when an obstacle is encountered. A method of moving the spa cover is also disclosed.

Abstract: A system for the accurate electronic detection and location of missiles, such as darts, is disclosed in which electromagnetic radiation is transmitted through a dart board to signal receiving elements positioned on the side of the dart board opposite the target face and the change in electromagnetic signal is detected when a dart is embedded in one of the dart board target areas. The larger signal receiving elements of the dart board are divided into signal sensing portions which are electrically distinct from adjacent smaller signal receiving elements of the target and also the remainder of the total area of the larger signal receiving element, and the sensing portions are located adjacent the smaller signal receiving elements of the target to improve the accuracy and reliability of the electrical scoring of the darts which become embedded in or close to the smaller signal receiving elements.