| 摘要 |
827,238. Lamps. EVER READY CO. (GREAT BRITAIN) Ltd., and WARBOYS, A. F. March 20, 1958 [March 29, 1957], No. 10432/57. Classes 39(2) and 75(2) An optical system for a battery lamp comprises two lenses 3, 4 each having a plane face and an undulatory face and being supported for relative angular movement from a position in which the crests on one undulatory face register with the troughs on the other undulatory face to provide a parallel light beam to a position in which the crests on the undulatory faces are in register to provide a divergent beam. The inner lens 4 has a threaded flange 14 screwed into the mouth of the battery lamp casing 13 and the end of a strip spring 17 engages in a slot 18 in the lens flange 14 to prevent rotation of the inner lens 4. The spring 17 is disengaged from the slot by depressing a button 20. The outer lens 3 is secured by a split ring 25 to a lens ring 22 which fits over the end of the lamp casing 13 and is retained in position by a pin 27 on the spring 17 engaging in a quadrantal groove 28 in the lens ring 22. A central stub 21 on the outer lens 3 engages in a central hole in the inner lens 4. A reflector 11 carrying a bulb 12 is a push fit in the flange 14 of the inner lens 4. In an alternative construction the outer lens has a cylindrical flange which fits frictionally over the inner lens. The lenses may be mounted with their plane faces opposed. The peaks and the bottoms of the undulations may be flattened. The undulations may be formed as a single volute or as a number of volutes of equal pitch which leave their common origin in directions equi-spaced around the origin. Alternatively the undulatory face of each lens may be formed as a number of sectors which are alternately concave and convex. |
