| 摘要 |
An artificial and natural lighting system placed in the roof of a building (12) that is substantially self-contained and powered. A photovoltaic cell (18; 118; 218) provides electricity stored in a battery (36; 236) to power light emitting diodes (26; 126; 226). A highly reflective interior coating (24) applied to the light shaft maximizes lighting intensity. A sensor (32; 132; 232) detects illumination intensity and temperature within the light shaft to control the balance of natural and artificial light provided to maintain predetermined illumination intensity. The light shaft is insulated to reduce heat transfer and a thermal collector removes heat from the building. In one embodiment, a Fresnel lens (16) is utilized to focus natural light onto the photovoltaic cell (18). In another embodiment, conventional fluorescent lighting (244) powered by external line voltage (248) is combined with light emitting diodes (218) powered primarily by a rechargeable battery (236). The present invention, being substantially self-contained, is easily retrofitted to existing buildings with a minimum of connections and provides substantial energy efficiencies in illuminating the building. |
