Abstract:
A projecting system is disclosed. The projecting system includes: a light source; a lens group disposed on the exit of the light source, wherein the lens group comprises a polarizing beam splitter; and at least one rectangular prism disposed on one side of the prism group and between the polarizing beam splitter and the light source.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to a projecting system and more particularly to a projecting system of having a prism between the polarizing beam splitter and the light source. 
         [0003]    2. Description of the Prior Art 
         [0004]    Projectors are conventionally used in conference briefings in which a host projects data or graphics onto a screen for familiarizing attendants with a presentation. With the rapid development of technology, projectors are now widely used in other applications. With high-power hi-fi equipment, large-capacity digital video discs (DVDs), and the large images that can be generated by projectors, it is now possible to reconstruct at home visual and audio effects similar to those provided in a movie theater. 
         [0005]    However, consumer projectors sold on market today typically have the disadvantage of insufficient brightness. For instance, after light is projected from a light source in a projecting system to a light-entering plane of a lens groups, the light is redefined through a polarizing beam splitter (PBS), reflected by a LCoS panel, and directed from a light-exit plane of the lens group to a projecting lens group. The projecting lens group then projects the corresponding image onto a screen. It should be noted that light projected from the light source onto the light-entering plane of the lens group is typically circular. However, as the light-entering plane of the lens group used for collecting light is built with a rectangular design, the mismatch between the light-entering plane of the lens group and the light produced from the light source often results in reduction of light and lowers the overall brightness of the display panel substantially. 
       SUMMARY OF THE INVENTION 
       [0006]    It is an objective of the present invention to provide a projecting system for solving the disadvantage of having insufficient brightness in current projecting system. 
         [0007]    According to a preferred embodiment of the present invention, a projecting system is disclosed. The projecting system includes: a light source; a lens group disposed on the exit of the light source, wherein the lens group comprises a polarizing beam splitter; and at least one rectangular prism disposed on one side of the prism group and between the polarizing beam splitter and the light source. 
         [0008]    According to another aspect of the present invention, a projecting system is disclosed. The projecting system includes: a light source; a lens group disposed on the exit of the light source, wherein the lens group comprises a polarizing beam splitter; and a plurality of segmented prism disposed on one side of the lens group and between the polarizing beam splitter and the light source. 
         [0009]    These and other objectives of the present invention will no doubt become obvious to those of ordinary skill in the art after reading the following detailed description of the preferred embodiment that is illustrated in the various figures and drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  illustrates a perspective view of a projecting system according to a preferred embodiment of the present invention. 
           [0011]      FIGS. 2-4  illustrate enlarged views of a prism of  FIG. 1  according to different embodiments of the present invention. 
           [0012]      FIG. 5  illustrates a perspective view of a projecting system according to another embodiment of the present invention. 
           [0013]      FIG. 6  illustrates an enlarged view of the segmented prism shown in  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    Referring to  FIG. 1 ,  FIG. 1  illustrates a perspective view of a projecting system according to a preferred embodiment of the present invention. Preferably, the projecting system could be constructed to project three-dimensional pictures or regular two-dimensional pictures, and an embodiment for projecting two-dimensional pictures is explained below. As shown in  FIG. 1 , the projecting system includes a light source  12 , a lens  28  for collecting light, a lens group  14 , a liquid crystal on silicon (LCoS) panel  16 , a prism  18  disposed on a light-entering plane  22  and a projecting lens group  20  disposed on a light-exit plane  24  of the lens group  14 . 
         [0015]    The light source  12  provides light required by the projecting system, in which the light source  12  could be composed of various light emitting elements including light emitting diodes (LEDs) or high intensity light bulbs. The lens  28  is situated between the light source  12  and the lens group  14 , and is preferably used to focus the light emitted from the light source  12  onto the light-entering plane  22  of the lens group  14 . Despite the lens  28  of this embodiment is composed of one single lens, the lens  28  could also be a composite lens structure with a plurality of lenses having focusing mechanisms, which is also within the scope of the present invention. 
         [0016]    The lens group  14  is situated relative to the exit of the light source  12 , in which the lens group  14  could include a polarizing beam splitter (PBS)  26  coating to redefine the unpolarized light beam projected from the light source  12  into P-polarizing beam and S-polarizing beam. The defined P-polarizing beam and the S-polarizing beam are reflected from the LCoS panel  16  to the projecting lens group  20 . The projecting lens group  20  is composed of a plurality of lenses and situated relative to the exit-plane  24  of the lens group  14  and opposite to the LCoS panel  16 . Light reflected from the LCoS panel  16  are directed through the projecting lens group  20  to a screen (not shown) to display a corresponding image. In this embodiment, the light-entering plane  22  of the lens group  14  is rectangular, hence the prism  18  is preferably rectangular or square. Nevertheless, the shape of the prism  18  could also be adjusted according to the shape of the light-entering plane  22  of the lens group  14 , which is within the scope of the present invention. The prism  18  is disposed between the polarizing beam splitter  26  of the lens group  14  and the light source  12 , and is preferably adhered onto the light-entering plane  22  of the lens group  14 . As light entering the lens group  14  first passes through the prism  18 , the prism  18  is preferably used to adjust and gather the light entering the lens group  14 , such that the LCoS panel  16  could receive much stronger light. 
         [0017]    Referring to  FIGS. 2-4 ,  FIGS. 2-4  illustrate enlarged views of the prism  18  according to different embodiments of the present invention. As shown in the figures, the prism  18  is fabricated according to the light-entering plane  22  of the lens group  14  with a central region  30  and a peripheral region  38 . The peripheral region  38  of the prism  18  includes four sides, in which each sides has at least one inclined surface  32 , and the inclined surface  32  could have equal or different slopes. As shown in  FIG. 2 , the peripheral region  38  of the prism  18  includes a total of four inclined surfaces  32  surrounding the rectangular central region  30 , in which each of the inclined surfaces  32  is a flat surface. However, one or more inclined surfaces  34 / 36  could be formed in the peripheral region  38 , as shown in  FIG. 3 , and the inclined surfaces  34 / 36  could have same or different slopes therebetween. In addition to flat surfaces, the surface  32  of the peripheral region  38  of the prism  18  is fabricated with an arced profile, as shown in  FIG. 4 . Overall, the peripheral region  38  of the aforementioned embodiments could be used to gather light emitted from the light source  12  to the lens group  14 , and the slope of the flat surface and degree of arced profile of the peripheral region  38  could all be adjusted according to the demand of the product. 
         [0018]    Referring to  FIG. 5 ,  FIG. 5  illustrates a perspective view of a projecting system according to another embodiment of the present invention. The projecting system of this embodiment could also be constructed to project three-dimensional pictures or regular two-dimensional pictures, and an embodiment for projecting two-dimensional pictures is explained below. As shown in  FIG. 5 , the projecting system includes a light source  42 , a lens  58  for collecting light, a lens group  44 , a liquid crystal on silicon (LCoS) panel  46 , a plurality of segmented prisms  48  disposed on a light-entering plane  52  and a projecting lens group  50  disposed on a light-exit plane  54  of the lens group  44 . 
         [0019]    Similar to the aforementioned embodiment, the light source  42  provides light required by the projecting system, in which the light source  42  could be composed of various light emitting elements including light emitting diodes (LEDs) or high intensity light bulbs. The lens  58  is situated between the light source  42  and the lens group  44 , and is preferably used to focus the light emitted from the light source  42  onto the light-entering plane  52  of the lens group  44 . Despite the lens  58  of this embodiment is composed of one single lens, the lens  58  could also be a composite lens structure with a plurality of lenses having focusing mechanisms, which is also within the scope of the present invention. 
         [0020]    The lens group  44  is situated relative to the exit of the light source  42 , in which the lens group  44  could include a polarizing beam splitter (PBS)  56  coating to redefine the unpolarized light beam projected from the light source  42  into P-polarizing beam and S-polarizing beam. The defined P-polarizing beam and the S-polarizing beam are reflected from the LCoS panel  46  to the projecting lens group  50 . The projecting lens group  50  is composed of a plurality of lenses and situated relative to the exit-plane  54  of the lens group  44  and opposite to the LCoS panel  46 . Light reflected from the LCoS panel  46  are directed through the projecting lens group  50  to a screen (not shown) to display a corresponding image. 
         [0021]    In contrast to the aforementioned rectangular prism  18 , a plurality of segmented prisms  48  is disposed on the light-entering plane  52  of the lens group  44 , in which the segmented prisms  48  are preferably composed of a frame consisting of four bar-shaped prisms. Referring to  FIG. 6 ,  FIG. 6  illustrates an enlarged view of the segmented prism  48  shown in  FIG. 5 . As shown in  FIG. 6 , the segmented prisms  48  include at least one inclined surface  60 , in which the inclined surfaces  60  could have equal or different slopes therebetween. Similar to the aforementioned embodiment of using peripheral region  38  of the lens  18  for adjusting and gathering light entering the PBS, the inclined surface  60  of this embodiment is preferably used for gather light entering the lens group  44 , such that more lights are collected and gathered on the lens group  44  and the LCoS panel  46  for displaying much better images. 
         [0022]    Despite the above embodiments are applied to a projecting system having one single LCoS panel as a base for projecting 2D images, the present invention could also apply the above embodiments to a projecting system with two LCoS panels for producing 3D images, which is also within the scope of the present invention. 
         [0023]    Those skilled in the art will readily observe that numerous modifications and alterations of the device and method may be made while retaining the teachings of the invention.