Light-generating device, for a ceiling light of a vehicle passenger compartment, characterized in that it comprises: - a separating tube made of a material that is opaque to the radiation used and intended to be placed in an aperture forming an exit for illuminating light, and which is tubular along an axis orthogonal to the aperture and has a radial cross section that is "c" shaped, so as to form an axial window, a bounding light guide, encircling the separating tube having: - an annular exit dioptric interface, - a base in the axial extension of the exit dioptric interface, axial extensions, which extend the base axially at least in part, comprising, at their end opposite the base, entrance dioptric interfaces, which are placed facing bounding light sources, - an illuminating light source, - a guide of illuminating light, which is located axially facing the illuminating light source and radially offset from the aperture, comprising: - an entrance dioptric interface, placed facing the illuminating light source, - a total-reflection surface, from which light entering through the entrance dioptric interface is reflected at a preset angle of inclination to the normal to the entrance dioptric interface, - an exit dioptric interface, through which the light reflected from the total-reflection surface is emitted in the direction of the aperture, the axial window being oriented in the direction of the light guide so that the beam generated by the illuminating light source and reflected by the total-reflection surface passes through said axial window and through the aperture. - a separating tube made of a material that is opaque to the radiation used and intended to be placed in an aperture forming an exit for illuminating light, and which is tubular along an axis orthogonal to the aperture and has a radial cross section that is "c" shaped, so as to form an axial window, a bounding light guide, encircling the separating tube having: - an annular exit dioptric interface, - a base in the axial extension of the exit dioptric interface, axial extensions, which extend the base axially at least in part, comprising, at their end opposite the base, entrance dioptric interfaces, which are placed facing bounding light sources, - an annular exit dioptric interface, - a base in the axial extension of the exit dioptric interface, - an illuminating light source, - a guide of illuminating light, which is located axially facing the illuminating light source and radially offset from the aperture, comprising: - an entrance dioptric interface, placed facing the illuminating light source, - a total-reflection surface, from which light entering through the entrance dioptric interface is reflected at a preset angle of inclination to the normal to the entrance dioptric interface, - an exit dioptric interface, through which the light reflected from the total-reflection surface is emitted in the direction of the aperture, - an entrance dioptric interface, placed facing the illuminating light source, - a total-reflection surface, from which light entering through the entrance dioptric interface is reflected at a preset angle of inclination to the normal to the entrance dioptric interface, - an exit dioptric interface, through which the light reflected from the total-reflection surface is emitted in the direction of the aperture,