Light source device including reflective film reflecting at least part of excitation light, and projector-type image display apparatus
View Patent ↗A light source device includes a solid light source, a transmissive fluorescent plate having a phosphor that is excited by excitation light for emitting fluorescent light in a traveling direction of the excitation light, and a color filter plate that cuts a part of a wavelength region of light supplied from the fluorescent plate for trimming the light into desirable color light. The light source device further includes a first reflective film disposed on a light path extending from the fluorescent plate to the color filter plate for reflecting at least a part of the excitation light.
1. A light source device comprising:
a solid light source;
a transmissive fluorescent plate including
a first region having a phosphor that is excited by excitation light supplied from the solid light source, the first region emitting fluorescent light from the phosphor and leakage excitation light not absorbed in the phosphor in a traveling direction of the excitation light from the solid light source, and
a second region through which the excitation light from the solid light source passes; and
a color filter plate including
a third region that the fluorescent light and the leakage excitation light emitted from the first region of the transmissive fluorescent plate enter,
a fourth region through which the excitation light from the second region of the transmissive fluorescent plate passes, and
a first reflective film that is disposed on the third region and reflects the leakage excitation light to the first region as a return excitation light.
2. The light source device according to claim 1 , wherein an optical system disposed from the transmissive fluorescent plate to the color filter plate forms a conjugate structure.
3. The light source device according to claim 1 further comprising an optical system that substantially collimates the light supplied from the transmissive fluorescent plate, wherein the light outgoing from the transmissive fluorescent plate enters substantially perpendicular to the color filter plate.
4. The light source device according to claim 1 , wherein the transmissive fluorescent plate is formed of: a transparent substrate; a second reflective film that is disposed on the transparent substrate and transmits the excitation light and yet reflects light having a different wavelength from the excitation light; and a phosphor painted on the second reflective film, and
wherein the phosphor transmits the excitation light incident on the phosphor at a given ratio.
5. A projector-type image display apparatus comprising:
the light source device as defined in claim 1 ;
a space conversion element that modulates illumination light supplied from the light source device with an image signal before emitting image light; and
a projection optical system that magnifies and projects the image light supplied from the space conversion element.
6. The light source device according to claim 1 , wherein the first reflective film reflects only the part of the excitation light.
7. The light source device according to claim 1 , wherein the transmissive fluorescent plate and the color filter plate are controlled such that the fluorescent light and the leakage excitation light from the first region enter the third region of the color filter, and the excitation light from the second region of the transmissive fluorescent plate passes through the fourth region.
8. The light source device according to claim 1 , wherein the fourth region is a light diffuser region creating blue reference light by diffusing the excitation light when the excitation light passes.