Abstract: A mercury-free metal halide arc lamp having an arc vessel of fused silica, an aspect ratio greater than 5, and containing a noble gas such as xenon, argon or krypton and a metal halide. In a preferred embodiment, the arc vessel has a diameter of 8 mm and a length of 80 mm, a fill of sodium/scandium iodides and a buffer gas of xenon.

Abstract: This invention relates to retroreflective sheeting which has an image, such as an image. More specifically, the image has varying appearance at different angles of view. The retroreflective sheeting has a layer of transparent microsphere lenses, a transparent polymeric spacing layer underlying, contacting, and conforming to the bottom of the lenses, the spacing and conformation of which is critical to the optimal performance of the retroreflective article, a reflective layer having a top surface in contact with the back surface of the spacing layer and a topcoat and/or cover sheet overlying and conforming to the top surfaces of the lenses and having a flat top surface or face. In another embodiment, the retroreflective sheeting includes a pressure sensitive adhesive underlying and in contact with the reflective layer. The retroreflective sheeting has an image whose proportions are determined by a non-conformity of the reflective and spacing layer to the bottom of the lenses.

Abstract: This invention relates to retroreflective sheeting which has an image, such as an image. More specifically, the image has varying appearance at different angles of view. The retroreflective sheeting has a layer of transparent microsphere lenses, a transparent polymeric spacing layer underlying, contacting, and conforming to the bottom of the lenses, the spacing and conformation of which is critical to the optimal performance of the retroreflective article, a reflective layer having a top surface in contact with the back surface of the spacing layer and a topcoat and/or cover sheet overlying and conforming to the top surfaces of the lenses and having a flat top surface or face. In another embodiment, the retroreflective sheeting includes a pressure sensitive adhesive underlying and in contact with the reflective layer. The retroreflective sheeting has an image whose proportions are determined by a non-conformity of the reflective and spacing layer to the bottom of the lenses.

Abstract: This invention relates to retroreflective sheeting which has an image, such as an image. More specifically, the image has varying appearance at different angles of view. The retroreflective sheeting has a layer of transparent microsphere lenses, a transparent polymeric spacing layer underlying, contacting, and conforming to the bottom of the lenses, the spacing and conformation of which is critical to the optimal performance of the retroreflective article, a reflective layer having a top surface in contact with the back surface of the spacing layer and a topcoat and/or cover sheet overlying and conforming to the top surfaces of the lenses and having a flat top surface or face. In another embodiment, the retroreflective sheeting includes a pressure sensitive adhesive underlying and in contact with the reflective layer. The retroreflective sheeting has an image whose proportions are determined by a non-conformity of the reflective and spacing layer to the bottom of the lenses.

Abstract: Rare-earth halides are shown to be a replacement for scandium halides in mercury-free discharge arc lamps if modifications are made to the prior art lamp design and operating temperatures. The inventive chemical compositions of the discharge medium provide enhanced color rendition index values. In addition, it has been unexpectedly determined that during the operation of the discharge lamps, the rare earth iodides do not react significantly with the fused silica arc tube. Equally as significant, any free iodine, which is so formed, has minimal impact on the efficacy of the lamp compared to the conventional scandium iodide lamps. Therefore, the rare earth iodide-containing lamps provide longer lifetime with superior illumination characteristics than conventional discharge lamps.

Abstract: This invention relates to retroreflective sheeting which has an image, such as an image. More specifically, the image has varying appearance at different angles of view. The retroreflective sheeting has a layer of transparent microsphere lenses, a transparent polymeric spacing layer underlying, contacting, and conforming to the bottom of the lenses, the spacing and conformation of which is critical to the optimal performance of the retroreflective article, a reflective layer having a top surface in contact with the back surface of the spacing layer and a topcoat and/or cover sheet overlying and conforming to the top surfaces of the lenses and having a flat top surface or face. In another embodiment, the retroreflective sheeting includes a pressure sensitive adhesive underlying and in contact with the reflective layer. The retroreflective sheeting has an image whose proportions are determined by a nonconformity of the reflective and spacing layer to the bottom of the lenses.

Abstract: This invention relates to retroreflective sheeting which has an image, such as an image. More specifically, the image has varying appearance at different angles of view. The retroreflective sheeting has a layer of transparent microsphere lenses, a transparent polymeric spacing layer underlying, contacting, and conforming to the bottom of the lenses, the spacing and conformation of which is critical to the optimal performance of the retroreflective article, a reflective layer having a top surface in contact with the back surface of the spacing layer and a topcoat and/or cover sheet overlying and conforming to the top surfaces of the lenses and having a flat top surface or face. In another embodiment, the retroreflective sheeting includes a pressure sensitive adhesive underlying and in contact with the reflective layer. The retroreflective sheeting has an image whose proportions are determined by a non-conformity of the reflective and spacing layer to the bottom of the lenses.

Abstract: A ballast for a mercury-free, metal halide arc lamp having a quartz or fused silica envelope. The ballast provides a square-wave voltage, which substantially reduces or eliminates the re-ignition voltage in the mercury-free, metal halide arc lamp. The ballast reverses the voltage polarity, and reestablishes the arc current in the opposite direction, before the free halogen in the envelope can quench the arc.

Abstract: A system and method for the operation of a mercury free high intensity discharge lamp is disclosed which provides lamp longevity and improved photometric results regardless of the orientation of the lamp. To this end, an acoustically modulated ballast without off-time and low power time is supplied to the lamp.

Abstract: An electrically fired flash lamp which utilizes a single conductive lead member. The lead protrudes within the lamp's envelope and is covered by a quantity of primer material. A conductive coating (e.g. tin oxide) covers a major portion of the external surface of the envelope and is capacitively coupled through the envelope's wall to the combustible filamentary material (e.g. shredded zirconium) therein. In another embodiment, a second conductive coating is located on the internal surface of the envelope opposite the outer coating and in electrical contact with the filamentary material. Accordingly, both coatings are capacitively coupled when the lamp is electrically fired. A sequentially-activated array of the above lamps is also disclosed.

Abstract: Several means are described for providing an electrical coupling path through a protective, insulative layer, e.g. cellulose acetate, located on an electrically activated flash lamp envelope. The function of the path is to interconnect a thin conductive coating positioned on the envelope's external surface under the insulative layer with an electrical contact located externally of the flash lamp and adapted for igniting the lamp.

Abstract: A circuit for operating an arc discharge flash lamp that is directly coupled across an alternating current (AC) source. The lamp is ignited by a high voltage pulse generated by a trigger circuit energized by the AC source. A voltage multiplier, such as a doubler circuit, is connected across the flash lamp for increasing the voltage across the lamp above that provided by the AC source, thereby facilitating starting of the lamp by the trigger circuit.