Electromagnetic disk and method of making

Abstract

A magnetic disk to selectively display opposite colored sides is constructed by providing upper, lower and middle tape layers. The middle layer is punched to provide a series of magnet receptacles when the upper and lower layers are added. The lower layer is added to the middle layer and the magnet inserted. The upper layer is applied and the magnet is magnetized before individual disk elements are detached from the tape. The upper layer may be constructed from a plurality of sub layers. The sub layers may be combined in a separate step before the upper layer is applied to the middle. The upper tape may be applied to the middle by pressure sensitive adhesive. The upper tape sub layers may be an outer clear layer and an inner colored layer, which clear layer may be treated for ultra violet filtering and to provide a matte finish. The sub layers in said upper layer may use a sub layer next to the middle layer which has a low linear coefficient of thermal expansion and preferably one similar to that of the lower layer. An upper sub layer when below a clear layer may be colored and translucent with a reflecting surface between the translucent sub layer and the middle layer. Such sub layers may include a fluorescent or retroflectant, or both. Disk produced by the process may be installed on a mount and have its dark side sprayed with a conducting coating.