Light source device and projection display apparatus

1. A light source device comprising:

a blue solid-state light source;

a red solid-state light source;

a first retardation plate that causes light from the blue solid-state light source to have a phase difference;

a dichroic mirror that provides the light from the blue solid-state light source with polarization separation, receiving the light from the blue solid-state light source and light from the red solid-state light source in an identical direction;

a phosphor plate that emits fluorescence light, excited by one light, separated by the dichroic mirror, of the light from the blue solid-state light source;

a second retardation plate that converts, into circular polarization, polarization of the light from the red solid-state light source and other light, separated by the dichroic mirror, of the light from the blue solid-state light source; and

a reflector that reflects light converted into circular polarization by being passed through the second retardation plate.

2. The light source device according to claim 1 , wherein the dichroic mirror combines the fluorescence light from the phosphor plate and the light reflected by the reflector.

3. The light source device according to claim 1 , wherein the first retardation plate is a quarter wavelength plate or a half wavelength plate.

4. The light source device according to claim 1 , wherein the first retardation plate has a structure in which a region having a retardation layer and a region having no retardation layer are formed on a glass substrate.

5. The light source device according to claim 1 , wherein the first retardation plate has a rotation adjustment mechanism.

6. The light source device according to claim 1 , wherein the second retardation plate is a quarter wavelength plate that causes quarter phase difference in a wavelength of the light from the blue solid-state light source and the light from the red solid-state light source.

7. The light source device according to claim 1 , wherein the first retardation plate and the second retardation plate are microstructured retardation plates each using birefringence by the microstructure.

8. The light source device according to claim 1 , wherein the first retardation plate and the second retardation plate are thin-film coating retardation plates each using birefringence by oblique deposition.

9. The light source device according to claim 1 , wherein the blue solid-state light source is a blue semiconductor laser.

10. The light source device according to claim 1 , wherein the red solid-state light source is a red semiconductor laser.

11. The light source device according to claim 1 , wherein the light from the blue solid-state light source and the light from the red solid-state light source are linearly-polarized light.

12. The light source device according to claim 1 , wherein the phosphor plate is a rotation-controllable circular plate and has a phosphor layer in which a Ce-doped YAG yellow phosphor containing green and red components is formed.

13. A projection display apparatus comprising:

the light source device described in claim 1 ;

an illumination optical system that collects light from the light source device and illuminates a region to be illuminated with the light;

an image forming element that forms an image in response to an image signal; and

a projection lens that magnifies and projects the image formed by the image forming element.

14. The projection display apparatus according to claim 13 , wherein the image forming element is a liquid crystal panel.

15. The projection display apparatus according to claim 13 , wherein the image forming element is a mirror-deflection digital micromirror device (DMD).