Cooling structure, lighting optical system, and projection-type display apparatus including substrate and phosphor formed on the substrate to emit fluorescent light

1. A cooling structure, comprising:

a phosphor unit that includes a substrate and a phosphor that is formed on said substrate and that emits fluorescent light by irradiation of excitation light;

an air-blowing system that causes cooling air to flow;

a duct structure that guides the cooling air from said air-blowing system to said phosphor unit,

wherein said duct structure includes a first flow path that guides the cooling air from said air-blowing system to a surface of said substrate on which said phosphor is formed and a second flow path that guides the cooling air from said air-blowing system to a region on a side of said substrate that is opposite to the surface on which said phosphor is formed;

a heat exchanger that decreases a temperature of the cooling air that has been heated in said phosphor unit; and

a plate-shaped partition member that forms a partition between said first flow path and said second flow path,

wherein a width of said first flow path that guides the cooling air from said air-blowing system to the surface of said substrate is less than a width of said second flow path that guides the cooling air from said air-blowing system to the region on the side of said substrate that is opposite to the surface on which said phosphor is formed.

2. A lighting optical system, comprising:

the cooling structure as set forth in claim 1 ; and

an excitation light source that emits excitation light that irradiates said phosphor.

3. A projection-type display apparatus, comprising:

the lighting optical system as set forth in claim 2 ;

an optical engine that converts light emitted from said lighting optical system to image light; and

a projection lens that projects said image light to outside.

4. The cooling structure as set forth in claim 1 , wherein said first flow path extends from said air-blowing system toward one end of said substrate.

5. The cooling structure as set forth in claim 1 , wherein said partition member approaches one end of said substrate.

6. The cooling structure as set forth in claim 1 , wherein said phosphor unit is disposed inside said duct structure.

7. The cooling structure as set forth in claim 1 , wherein said first flow path includes a constricted portion in which a flow path width decreases as the first flow path progresses toward an irradiation spot of said excitation light of said phosphor.

8. The cooling structure as set forth in claim 1 , further comprising:

a heat sink; and

another air-blowing system that causes the cooling air to blow against said heat sink.

9. A cooling structure, comprising:

a phosphor unit that includes a substrate and a phosphor that is formed on said substrate and that emits fluorescent light by irradiation of excitation light;

an air-blowing system that causes cooling air to flow;

a duct structure that guides the cooling air from said air-blowing system to said phosphor unit,

wherein said duct structure includes a first flow path that guides the cooling air from said air-blowing system to a surface of said substrate on which said phosphor is formed and a second flow path that guides the cooling air from said air-blowing system to a region on the side of said substrate that is opposite to the surface on which said phosphor is formed, and

wherein said phosphor unit is disposed inside said duct structure; and

a plate-shaped partition member that forms a partition between said first flow path and said second flow path,

wherein a width of said first flow path that guides the cooling air from said air-blowing system to the surface of said substrate is less than a width of said second flow path that guides the cooling air from said air-blowing system to the region on the side of said substrate that is opposite to the surface on which said phosphor is formed.

10. The cooling structure as set forth in claim 9 , wherein said first flow path includes a constricted portion in which a flow path width decreases as it progresses toward an irradiation spot of said excitation light of said phosphor.

11. The cooling structure as set forth in claim 10 , wherein an end of said constricted portion is directed toward the irradiation spot of said excitation light.

12. The cooling structure as set forth in claim 9 , further comprising:

a drive motor that is provided in said second flow path and that drives a rotation of said substrate.

13. The cooling structure as set forth in claim 12 , further comprising:

a heat sink that is attached to said drive motor, and

another air-blowing system that causes the cooling air to blow against said heat sink.

14. The cooling structure as set forth in claim 9 , further comprising:

a heat exchanger that decreases a temperature of said cooling air that has been heated in said phosphor unit.

15. The cooling structure as set forth in claim 9 , wherein said first flow path extends from said air-blowing system toward one end of said substrate.

16. A cooling method for cooling a phosphor unit that contains a substrate and a phosphor that is formed on said substrate and that produces fluorescent light by irradiation of excitation light, the method comprising:

directing cooling air against said phosphor unit by way of a duct structure that guides the cooling air from an air-blowing system to said phosphor unit; and

guiding, through a first flow path, the cooling air to a surface of said substrate on which said phosphor is formed, and guiding, through a second flow path, the cooling air to a region on a side of said substrate that is opposite to the surface on which said phosphor is formed,

wherein said phosphor unit is disposed inside said duct structure,

wherein a plate-shaped partition member forms a partition between said first flow path and said second flow path, and

wherein a width of said first flow path that guides the cooling air from said air-blowing system to the surface of said substrate is less than a width of said second flow path that guides the cooling air from said air-blowing system to the region on the side of said substrate that is opposite to the surface on which said phosphor is formed.

17. The cooling method as set forth in claim 16 , further comprising:

decreasing, in a heat exchanger, a temperature of the cooling air that has been heated in said phosphor unit.