Projector-type head lamp for motor vehicles.

摘要

In a projector-type head lamp, a reflector (10) having a concave inner reflecting surface (12), a light source (14), a shade (16) with a cut-off edge (18) and a projection lens (20) are arranged in order. The inner reflecting surface (12) of the reflector (10) has at least 2 focii and is so designed as to reflect the rays of light emitted from the light source (14) in a direction crossing the optical axis (z). The light source (14) is disposed near one of the focii of the reflector while the cut-off edge (18) of the shade (16) is arranged in the vicinity of the other focus. The projection lens (20) has an optical axis nearly coincident with that of the reflector (10) and is so formed that the power of refraction thereof becomes little by little greater from the optical axis toward the outer circumference, namely, its peripheral lens area (A1) has a focus located in the vicinity of the cut-off edge (18) while its central lens area (A4) has a focus located between the cut-off edge and the light source. The colored rays having passed through the peripheral lens area (A1) near the outer circumference of the projection lens form a sharp image of the cut-off edge (18) of the shade (16) on a screen, while the white rays having passed through the central lens area (A4) in which the optical axis lies form a blurr image of the cut-off edge (18) on the screen. In an illumination pattern defined on the screen, the color fringes formed in the vicinity of the cut-off line are covered by the blurr image defined by the white rays having passed through the central lens area (A4), thereby making the color fringes sufficiently unnoticeable.