| 摘要 |
A vehicle headlamp is constructed with its reflector and front lens adapted to be fixedly mounted in the bodywork of the vehicle, but incorporates a beam deflecting system, in order that the direction of the beam may nonetheless be adjusted. In one form, the beam deflecting system comprises two Fresnel lenses, mounted face to face in a position to intercept the whole of the headlamp beam, one being equivalent to a diverging lens with cylindrical surfaces, and one being equivalent to a converging lens with cylindrical surfaces. In a neutral position, the effects of the two lenses cancel out, so that no deflection of the beam occurs. One of the lenses is movable in translation away from the neutral position, so that a deflection of the beam occurs, without any other change in the beam pattern. In modified embodiments, the stationary Fresnel lens is not used; instead, its effect is produced by using a reflector of modified shape.
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