Abstract: A projection curtain is provided in the present invention. The projection curtain at least comprises a reflective layer and one of a colored layer, a diffusion layer, and a Fresnel lens layer. The Fresnel lens layer is a spherical Fresnel lens layer or an aspherical Fresnel lens layer. The Fresnel lens layer comprises a plurality of annular protrusions protruding from a plane, the plurality of annular protrusions are arranged in circular bands. A cross-sectional shape of each annular protrusion along a cross section perpendicular to the plane is a triangular shape or a multi-step shape or a free surface shape. The width of one side of each cross-sectional shape parallel to the plane gradually changes, and gradual change of the cross-sectional shape and the width thereof determines light gathering characteristics of the spherical Fresnel lens layer or the aspherical Fresnel lens layer. A surface of each annular protrusion has scattered microstructures.

Abstract: An x-ray protection circuit for a video processor, to disable a horizontal output pulse when a voltage level on the x-ray input exceeds a reference voltage. The x-ray protection circuit comprises a comparator and a bistable device, and incorporates a reset circuit. The reset circuit enables the initialisation of the protection circuit whilst the power is switched on.