A light source assembly includes a light source which emits light; a detector which detects the light and generates a light signal based on a property of the light; an operator operably connected to the detector and which receives the light signal and calculates a color coordinate of the light source based on the light signal; a comparator operably connected to the operator and which compares the color coordinate of the light source to a predetermined reference color coordinate; and a control unit operably connected to the comparator and which controls a pulse width modulation signal transmitted to the light source based on a result of the comparison of the comparator.