Patent GB-818164-A (GB)
Title: Improvements in headlamps
IPC: F21S8/10
Filed: 1956-08-20
Abstract: 818,164. Vehicle headlamps. ERBSLOH, P. G. Aug. 20, 1956 [Aug. 19, 1956; Nov. 10, 1955; June 25, 1956], No. 25373/56. Classes 75(2) and 75(4) [Also in Group XXXVII] In a vehicle headlamp comprising a parabolic reflector 2 with a double filament bulb 4 provided for bright and dipped illumination, the dipped beam 16, Fig. 8, is augmented by a beam 14 having a sharp vertical cut-off. 14<SP>1</SP>, Fig. 6, on the off-side, the beam 14 being produced by a single filament bulb 5 in a separate parabolic reflector 3 disposed co-axially with the reflector 2 in the same housing 1 to direct the beam either through a rear opening 2<SP>1</SP> thereof, Fig. 1, or around the outer periphery thereof, Fig. 13, and the cut-off 14<SP>1</SP> being achieved by a screen of vertically disposed spaced slats or glass laminae 8, 9 inclined at a small angle to the lamp axis and disposed in front of the reflector 3. As shown in Figs. 1-3, the reflector 3 and its associated screens 8, 9 are mounted for axial adjustment relative to and rearwardly of the reflector 2 with the reflector 3 dimensioned to lap the rear opening 2<SP>1</SP> of the reflector 2. The front glass 12 of the lamp is provided with a clear central portion axially opposite the reflector 3 whereas the annular portion 12<SP>1</SP> aligned with the surface of the reflector 2 is provided with diffusing flutes. The slats comprising the screen 8, 9 are arranged in groups having relatively different spacing and horizontal inclination to the optical axis to provide the desired beam cut-off. If desired, additional beam deflection may be achieved by the provision of prisms 31 either in front of or behind the screen 8, 9 and the slats and prisms may be arranged so as to produce a beam 14 having its greatest intensity adjacent the cut-off 14a with a gradual fall in intensity therefrom towards the near-side of the road. In a further arrangement, Figs. 14 and 17, the screen comprises upper and lower groups 9, 9<SP>1</SP>, of slats and two lateral groups 8, 8<SP>1</SP> which have closer spacing than those of the groups 9, 9<SP>1</SP>. The respective beams of the lamp are strengthened by auxiliary reflectors 45, 46 associated respectively with the bulbs 4, 5, and the lamp glass 12 has its central clear portion provided with upper and lower light deflecting prisms 43, 43<SP>1</SP> for the beam 14. Alternatively, prisms 59, 59<SP>1</SP> are provided on, or in front of, the screen 8, 9. The reflector 2 may have a zone 2<SP>11</SP> at its upper rear periphery which is fluted to diffuse the light from the "dipped" filament of the bulb 4. To facilitate access to the bulb 5, the reflector and bulb assembly 2, 4 may be pivoted at 48 to a frame 47 whereby the assembly may be swung away from the reflector 3. The bulb 5 may be switched for operation separately from or together with either the dipped or bright filaments of the bulb 4, and Fig. 20 shows a switch arrangement which may be fitted over the conventional foot-operated dipswitch. The arrangement comprises a cylindrical body 51 of resilient rubber or the like with a hollow cap end 57 housing contacts 52, 53 connected with the supply cables 54, 55 which are received in a cable entry 56 integral with the body 51. A rivet 58 in the end cap wall 57 serves to bridge the contacts, on foot pressure applied to the cap 57, to operate bulb 5, subsequent further pressure effecting operation of the dip switch proper to operate one or other of the filaments of bulb 4.