Current architectures of projectors mainly include an illumination system, a light valve, and a projection lens. The illumination system is used for providing an illumination beam. The light valve is used for converting the illumination beam into an image beam. The projection lens is used for projecting the image beam onto a screen to form image pictures on the screen. The illumination system can generate illumination beams of different colors. A main principle is to excite phosphors on phosphor wheels through the light emitted from laser diodes having good luminous efficiency, and thereby to generate a desired pure color light source.
In light path architectures of projectors, a source of blue color light in the image pictures is a blue laser diode. In order to excite the phosphors on the phosphor wheels and achieve good efficiencies for conversion to different color lights, laser diodes that can emit short-wavelength blue light (i.e., blue light with a wavelength less than 445 nm) are used. But the short-wavelength blue light is a purplish blue light in the sense of human eyes. Therefore, in order to improve the quality of the image pictures, the purplish blue light must be adjusted to a blue light close to bluish. However, laser diodes have extremely narrow bandwidth with monochromaticity. Chromaticity coordinate values of the blue light, emitted by the laser diodes, in CIE1931 color space have been very close to critical values of the color space. Thus, the purplish blue light cannot be further purified through multicolor light filters to achieve desired chromaticity coordinate values in the color space.
Therefore, how to improve above-mentioned problems is really a focus for relevant people in the field.
The information disclosed in this “BACKGROUND OF THE INVENTION” section is only for enhancement understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art. Furthermore, the information disclosed in this “BACKGROUND OF THE INVENTION” section does not mean that one or more problems to be solved by one or more embodiments of the invention were acknowledged by a person of ordinary skill in the art.