Patent Application
20070296925
The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention, and together with the description, serve to explain the principles of the invention.
Firstly, the white light 212 is focused on the polarization beam splitter converter 240 by the first integral lens array 220 and the cylindrical lens array 230, wherein the cylindrical lens array 230 specially reduces the geometry length of the light spot formed by focusing the white light 212 in the horizontal direction (i.e. X-axis) for the light spot to nearly completely pass through the polarization beam splitter converter 240. In the next step, the polarization beam splitter converter 240 converts the white light 212 into a polarized light, and the cylindrical lens 250 rectifies the light spot with an asymmetric shape (i.e. asymmetric X and Y directions) into a light spot with a desired shape and scale. The following step is that the white light 212 is focused on the collimator lens 270 by the condenser lens 260 again, and the collimator lens 270 is suitable for converting the white light 212 into a nearly parallel light beam.
As described above, since after the white light 212 is focused on the polarization beam splitter converter 240, the scale of the light spot can nearly completely pass through the polarization beam splitter converter 240, the present invention can effectively improve the light utilization of the illumination system 200. The light utilization is the ultimate ratio of the illumination of the white light 212 provided by the illumination system 200 to the illumination of the white light 212 initially emitted from the light source module 210. In addition, in the projection system 20 of the present invention, the liquid crystal display panel 202 is disposed on the optical path of the white light 212 provided by the illumination system 200, such that the white light 212 can be first converted into an imaged and then projected. Since the illumination system 200 provides better light utilization, the projection system 20 having the illumination system 200 provides better light utilization. The liquid crystal display panel 202 is a reflective liquid crystal display panel or a transmissive liquid crystal display panel and the reflective liquid crystal display panel is a LCOS (Liquid Crystal On Silicon) display panel.
The configuration of the first integral lens array 220, the cylindrical lens array 230, and the polarization beam splitter converter 240 in the illumination system 200 is described in greater detail with referring to the accompanying drawings hereinafter.
When the white light 212 with both p and s polarization states is emitted onto the polarization beam splitter converter 240 through the transparent region 242, the polarized light separation film 246 is suitable for freely passing through the white light 212 with the p polarization state and reflecting the white light 212 with the s polarization state. After being reflected by the reflecting film 248, the white light 212 with the s polarization state is directly emerged from the emergence surface of the polarization beam splitter converter 240. The white light 212 with the p polarization state is converted into the white light 212 with the s polarization state by the half-wave plate 249. Accordingly, the polarization state of the white light 112 is converted into a polarization state of single polarization direction.
Table 1 provides description of the relationship between the light utilization and the curvature of the cylindrical lens in the cylindrical lens array. Referring to table 1, when the radius of the cylindrical lens 232 in the cylindrical lens array 230 is between 5 to 25 mm, the light utilization of the illumination system 200 provided by the present invention 200 are higher than the conventional illumination system where the cylindrical lens array is not installed (91.48%) and the light utilization is a ratio of the illumination of the white light finally provided by the illumination system to the illumination of the white light initially emitted from the light source module. Considering the manufacturing cost and light emitting effect, the optimal curvature of the cylindrical lens 232 in the cylindrical lens array 230 is 20 mm.
Referring to
In summary, the illumination system and the projection system of the present invention at least have following advantages:
1. A cylindrical lens array is disposed in the present invention to adjust the shape of the light spot, such that the light spot can nearly completely pass through the polarization beam splitter converter with the illumination system of better light utilization. In addition, since the illumination system with a better light utilization is disposed in the projection system, the projection system of the present invention can provide better light utilization.
2. Comparing to the conventional technique where a second integral lens array with a special specification has to be installed, the light spot is rectified by the cooperation of the cylindrical lens array and the cylindrical lens in the present invention. A second integral lens array with a common specification is used in the present invention to replace the second integral lens array with a special specification, such that the manufacturing cost is reduced.
3. Since the illumination system of the present invention is not assembled as symmetrical to the center light axis, it is very easy to assemble the illumination system 200 in the mass production with lower manufacturing cost.
Although the invention has been described with reference to a particular embodiment thereof, it will be apparent to one of the ordinary skills in the art that modifications to the described embodiment may be made without departing from the spirit of the invention. Accordingly, the scope of the invention will be defined by the attached claims not by the above detailed description.
