Multi-color traffic signal

Multi-color traffic signal in particular for railway line signalling installations, of the type presenting for each color a projector unit (7, 8, 9) comprising a light source (4, 5, 6), an optical unit (10, 11) and a chromatic filter (12, 13, 14), the projector units being connected to an irradiating output optics (2, 3) by means of an optical channel system (15, 16, 17), and the projector units being controlled so that only one unit produces a light beam at any given time, characterized by the fact that the said optical channel system comprises a main rectilinear channel (15) presenting at one end the irradiating output optics (2, 3) and at the other end a first projector unit (7) in axial alignment with said main channel (15), second and third projector units (8, 9) being housed in transverse channels (16, 17) arranged at 90.degree. with respect to the said main channel (15) and opening thereinto, a first dichroic mirror (18) being arranged in the main channel with an angle of 45.degree., in correspondence with the outlet of the transverse channel of the second projector unit, and a second dichroic mirror (19) being arranged in the main channel with an angle of 45.degree. in correspondence with the outlet of the transverse channel of the third projector unit, each said dichroic mirror (18, 19) being spectrophotometrically adjusted with respect to the bands of wave length of the colored lights produced by the said projector units (7, 8, 9), each said dichroic mirror (18, 19) being arranged, at the interior of the optical channel system, in such a manner as to reflect towards the irradiating output optics (2, 3) the colored light beam produced by a projector unit (8, 9) associated thereto, while it permits the passage towards the said irradiating output unit (2, 3) of the colored light beams produced by the remaining projector units (7, 8), and each said projector unit producing a light beam of a respectively different color.