| 摘要 |
950,284. Electric bulbs with incandescent filaments. K. SASSMANNSHAUSEN. April 24, 1961 [April 22, 1960], No. 14789/61. Heading H1F. [Also in Divisions F4 and G2] A lamp, especially a vehicle lamp or a hand lamp has an incandescent electric bulb the filament of which is enclosed in a glass envelope, part of which in front of the filament is formed as a convergent lens by which part of the light from the filament is collected into a convergent beam having a apical angle between 40 and 75 degrees and a concave reflector, the bulb being mounted with the filament at the focal point of the reflector so that part of the light is reflected to form a beam of a maximum apex angle of 10 degrees, the two parts of the light being influenced only by the lens and by the reflector, respectively. The axes of the lens and reflector may coincide or may be inclined at an angle of from 15 to 70 degrees. The lens preferably subtends an angle of from 90 to 150 degrees at the part of the filament closest to the lens. The radius of the outer surface of the lens may increase from the centre to the periphery, the outer surface being, for example, hyperbolic in cross-section, and the radius of the inner surface may decrease from the centre to the periphery, the cross-section being, for example, elliptical, with the minor axis of the ellipse coinciding with the optical axis. In the form shown, the filament 22, the edge of the lens 50 and the rim of the reflector 20 are collinear, forming an angle of 110 degrees at the filament. The bulb has a flange 35 on the wall of the cap 30 fitting into a cylindrical holder 36 on the reflector. The envelope of the bulb has a narrow shoulder 48 and is fixed in front as a lens 50. The leading-in wires 58 are held together by a glass bead 60 and one bent back from the filament to extend behind the shoulder 48. The diameter of the lens is at least 7 mm. and the distance (XW) from the nearest point of the lens to the filament is from 55 to 100% of the lens diameter to avoid blackening. The filament is preferably spaced at 4-10 mm. from the flange 35, the thickness (XY) of the inner lens dome is 15- 30% of the lens diameter and the thickening (YZ) of the outer lens dome is 3 mm. Specification 950,283 is referred to. |
