Illumination system and projection apparatus

1. An illumination system, comprising:

a light source configured to emit an illumination beam;

a filtering module disposed on a transmission path of the illumination beam and comprising a plurality of filtering units of different colors, the filtering units moving into the transmission path of the illumination path in turn, wherein each of the filtering units reflects a part of the illumination beam and allows another part of the illumination beam to pass through;

a wavelength conversion unit disposed on a transmission path of the part of the illumination beam reflected by at least one of the filtering units to convert the part of the illumination beam reflected by the at least one of the filtering units into a converted beam; and

a reflection unit, wherein the wavelength conversion unit is disposed on the reflection unit, the reflection unit reflects the converted beam to the at least one of the filtering units, and at least a part of the converted beam passes through the at least one of the filtering units.

2. The illumination system as claimed in claim 1 , wherein the wavelength conversion unit is a fluorescent layer.

3. The illumination system as claimed in claim 2 , wherein the fluorescent layer comprises a phosphor in a single color.

4. The illumination system as claimed in claim 2 , wherein the fluorescent layer comprises a phosphor in a first color, a phosphor in a second color, and a third phosphor in a third color, and a color of the filtering units comprises the first color, the second color, and the third color.

5. The illumination system as claimed in claim 4 , wherein the filtering module further comprises a multi-layer optical coating layer disposed on the filtering units and between the wavelength conversion unit and the filtering units for a part of the converted beam from the wavelength conversion unit and the part of the illumination beam reflected by the filtering unit and not converted by the wavelength conversion unit to reflect back to the wavelength conversion unit.

6. The illumination system as claimed in claim 1 , wherein the filtering module is a color wheel.

7. The illumination system as claimed in claim 1 , wherein the reflection unit is a concave mirror to converge the converted beam on the at least one of the filtering units.

8. The illumination system as claimed in claim 1 , wherein the reflection unit is a reflection sleeve disposed between the light source and the filtering module, and the illumination beam is transmitted in the reflection sleeve.

9. The illumination system as claimed in claim 1 , wherein an optical axis of the light source tilts relative to the filtering units and an optical axis of the reflection unit tilts relative to the filtering units.

10. A projection apparatus, comprising:

an illumination system, comprising:

a light source configured to emit an illumination beam;

a filtering module disposed on a transmission path of the illumination beam and comprising a plurality of filtering units of different colors, the filtering units moving into the transmission path of the illumination path in turn, wherein each of the filtering units reflects a part of the illumination beam and allows another part of the illumination beam to pass through;

a wavelength conversion unit disposed on a transmission path of the part of the illumination beam reflected by at least one of the filtering units to convert the part of the illumination beam reflected by the at least one of the filtering units into a converted beam; and

a reflection unit, wherein the wavelength conversion unit is disposed on the reflection unit, the reflection unit reflects the converted beam to the at least one of the filtering units, and at least a part of the converted beam passes through the at least one of the filtering units;

a light valve disposed on a transmission path of the another part of the illumination beam passing through the at least one of the filtering units and the at least a part of the converted beam to convert the another part of the illumination beam passing through the at least one of the filtering units and the at least a part of the converted beam into an image beam; and

a projection lens disposed on a transmission path of the image beam.

11. The projection apparatus as claimed in claim 10 , wherein the wavelength conversion unit is a fluorescent layer.

12. The projection apparatus as claimed in claim 11 , wherein the fluorescent layer comprises a phosphor in a single color.

13. The projection apparatus as claimed in claim 11 , wherein the fluorescent layer comprises a phosphor in a first color, a phosphor in a second color, and a third phosphor in a third color, and a color of the filtering units comprises the first color, the second color, and the third color.

14. The projection apparatus as claimed in claim 13 , wherein the filtering module further comprises a multi-layer optical coating layer disposed on the filtering units and between the wavelength conversion unit and the filtering units for a part of the converted beam from the wavelength conversion unit and the part of the illumination beam reflected by the filtering unit and not converted by the wavelength conversion unit to reflect back to the wavelength conversion unit.

15. The projection apparatus as claimed in claim 10 , wherein the filtering module is a color wheel.

16. The projection apparatus as claimed in claim 10 , wherein the reflection unit is a concave mirror to converge the converted beam on the filtering units.

17. The projection apparatus as claimed in claim 10 , wherein the reflection unit is a reflection sleeve disposed between the light source and the filtering module, and the illumination beam is transmitted in the reflection sleeve.

18. The projection apparatus as claimed in claim 10 , wherein an optical axis of the light source tilts relative to the filtering units and an optical axis of the reflection unit tilts relative to the filtering units.