| 摘要 |
554,369. Luminairs. HOLOPHANE. Ltd., (Holophane, Co., Inc.). Sept. 14, 1942, No. 12936. [Class 75 (ii)] A luminair having a light source extending to or concentrated at two points 11, 12 on opposite sides of its axis B-B of symmetry is fitted with a lens 13 of the Fresnel type formed with prisms shaped so that all rays such as 14<SP>1</SP>, 15<SP>1</SP> from the source 11 falling on the lens 13 to the left of the axis B-B and all ray such as 14, 15 from the source 12 falling on the lens 13 to the right of the axis B-B are refracted so as to emerge as rays 22<SP>1</SP>, 21<SP>1</SP>, 22, 21, parallel to the axis B-B, while the rays 17', 18<SP>1</SP> and 17, 18 crossing the axis emerge as two parallel divergent beams. If the points 11, 12 are diametrally opposite points on a ring filament of a high wattage lamp the lens may consist of a round plate formed by the revolution of the diametral strip about the axis B-B. If the source of light consists of luminous strip formed by two tubular lamps the lens consists of a plate formed by moving the strip shown at right angles to its plane. The lens so formed comprises light refracting elements whose refracting power decreases from the middle to a region of zero refracting power and beyond this region increases in refracting power to a value substantially greater than that at the middle. |
