Passive display device

摘要

A passive display device particularly useful for signs and reflectors and not requiring any light source characterized by a device for entrapping light and then emitting entrapped light at given positions at an increased intensity. The device for entrapping light includes at least one transparent fluorescent member having an index or refraction greater than 1 and containing fluorescent particles which collect impinging light by fluorescent scattering with subsequent reflection on the boundary surface of the member and the device has output coupling zones which are disposed on one of the members such as the fluorescent member in a desired pattern for uncoupling light from the device in a desired pattern. The device may include phosphorescent particles, which will emit light during periods of darkness and which may be either scattered through a member or applied at the uncoupling zones so that the light being uncoupled is a phosphorescent light. The device may include more than one member which will entrap light and preferably all of the elements of the device will act to entrap light with some of the members being free of fluorescent particles while others contain the fluorescent particles.