Abstract: In a system for optically performing position detection and data communication, a transmitting apparatus has first and second light-emitting elements for position indication and data transmission. An image sensing element in a receiving apparatus senses the light-emitting elements. Position is detected from the sensed image of the first light-emitting elements using triangulation, and data communication is performed by blinking the second light-emitting element. This system is used in a hospital where the use of radio waves is restricted or outerspace where the system is exposed to strong electromagnetic waves.

Abstract: A water-based coating composition which cures through a Michael reaction at room temperature is provided. The composition comprises (a) an aqueous emulsion of an acrylic copolymer having a plurality of activated methylene groups in the molecule, (b) an aqueous dispersion or solution of a compound having a plurality of ethylenic unsaturations in the molecule, and (c) a compound capable of catalyzing the Michael reaction.