Image projection system with an invisible-light reflector for heat dissipation

1. An image projection system comprising:

a light source for generating a light beam;

a reflective housing comprising an opening, the opening having a diameter smaller than a maximum diameter of the reflective housing, the reflective housing forming an accommodating space, the light source installed inside the accommodating space so that the light beam generated by the light source substantially propagates along an optical path through the opening away from the accommodating space, wherein the reflective housing is substantially parabolic shaped, and the optical path is a substantially parallel route by which the light beam propagates after being reflected by the parabolic reflective housing; and

an invisible-light reflector installed at a reflecting position intersecting with the optical path outside the opening of the reflective housing, a normal of the invisible-light reflector and the optical path intersecting to form a predetermined angle so that invisible light of the light beam emitted from the opening will be reflected back into the accommodating space;

wherein the predetermined angle formed by the normal of the invisible-light reflector and the optical path is an acute angle not equal to zero degrees, so that infrared rays of the light beam reflected back into the accommodating space by the invisible-light reflector will not focus on the reflective housing.

2. The image projection system of claim 1 , wherein the image projection system further comprising a light tube connected to the light source, wherein the infrared rays of the light beam reflected back into the accommodating space by the invisible-light reflector will not focus on the light tube.

3. The image projection system of claim 1 , wherein the acute angle is smaller than 45 degrees.

4. The image projection system of claim 1 , wherein the image projection system further comprises an image module, the image module comprising a plurality of controllable optical reflectors for modulating the light beam passing through the invisible-light reflector to generate a projecting beam containing an optical image, wherein the light beam passing through the invisible-light reflector does not comprise the infrared rays.

5. The image projection system of claim 4 , wherein the image module is a digital micro-mirror device.

6. The image projection system of claim 1 , further comprising an image module, wherein the image module is a liquid crystal panel.

7. The image projection system of claim 1 , wherein the invisible-light reflector is immediately adjacent to the reflective housing along the optical path.

8. An image projection system comprising:

a light source for generating a light beam;

a parabolic reflective housing comprising an opening, the parabolic reflective housing forming an accommodating space, the light source installed inside the accommodating space so that the light beam generated by the light source substantially propagates along an optical path through the opening away from the accommodating space; and

an invisible-light reflector installed at a reflecting position intersecting with the optical path outside the opening of the parabolic reflective housing, a normal of the invisible-light reflector and the optical path intersecting to form a predetermined angle so that invisible light of the light beam emitted from the opening will be reflected back into the accommodating space;

wherein the predetermined angle formed by the normal of the invisible-light reflector and the optical path is an acute angle not equal to zero degrees, so that infrared rays of the light beam reflected back into the accommodating space by the invisible-light reflector will not focus on the parabolic reflective housing.

9. The image projection system of claim 8 , wherein the optical path is a parallel route by which the light beam propagates after being reflected by the parabolic reflective housing.