Light source device and projector using the same

A light source device of a projector which irradiates blue light, red light, and green light in turn on an image-forming element and forms a color image on a screen by the image-forming element, comprising:

• a light source section which generates any one of the blue light, the red light, and the green light;
• a phosphor which generates fluorescence including the two colors other than the color of the light emitted from the light source section through irradiation of the color light emitted from the light source section;
• a color-changing section which changes one of the two colors of the fluorescence emitted from the phosphor to another fluorescence color regularly and irradiates it to the image-forming element;
• and
• a light path-switching section which is disposed in a light path of the color light emitted from the light source section, and switches a light path of the color light emitted from the light source section between a light path in which a fluorescence excited by the color light emitted from the light source section passes towards the color-changing section and a light path in which the color light emitted from the light source section passes towards the image-forming element regularly.