Patent Publication Number: US-2010110388-A1

Title: Light-source module and projector having same

Description:
TECHNICAL FIELD 
     The present disclosure relates to projectors and, particularly, to a compact light-source module and a projector having the same. 
     DESCRIPTION OF THE RELATED ART 
     Projectors are known to typically include a light-source module having at least one light source, an electro-optical device for forming an optical image according to image information by using light beams emitted from the light sources, a projection lens for enlarging and projecting the optical image formed by the electro-optical device, and an outer casing for housing these components. Such projectors are widely used for multimedia presentations at conferences, academic meetings, exhibitions, and the like. 
     A typical light-source module for a projector usually has at least one light source, and at least one converging lens corresponding to each light source for converging the light emitted from the corresponding light source. In order to keep a certain distance for the converging lens from the corresponding light source, typically, the converging lens are assembled in the light-source module by securing the converging lens to secure portions, such as frames and so on. As a result, the light-source module is usually bulky and difficult to be assembled. 
     What is needed, therefore, is a projector with a compact light-source module to overcome the above-described problems. 
     BRIEF DESCRIPTION OF THE DRAWING 
     Many aspects of the present light-source module and projector can be better understood with references to the accompanying drawings. The components in the drawing are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present light-source module and projector. 
     The drawing is a schematic, partially exploded view of a projector according to an exemplary embodiment. 
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present disclosure will now be described in detail below, with reference to the accompanying drawing. 
     Referring to the drawing, a projector  100  according to an exemplary embodiment is shown. The projector  100  includes a light-source module  10 , an electro-optical device (not visible), and a projection lens module  20 . In the present embodiment, the electro-optical device is a digital micromirror device (DMD). 
     The projector  100  can project an image onto a screen (not shown). The formation of the image on a screen may be accomplished by the following process: firstly, light emitted from the light-source module  10  is concentrated and reflected to the DMD by optical components (not shown), such as converging lens and reflecting mirror. The DMD then reflects the light and produces the image towards the projection lens module  20  which focusing the image and then projects the image onto the screen. 
     The light-source module  10  includes a casing  11 , and at least one light-source unit  12 . In the present embodiment, the light-source module  10  includes three light-source units  12 . 
     The casing  11  is substantially a cube including a first sidewall  111  adjacent to the projection lens module  20 , an opposite second sidewall  112  away from the projection lens module  20 , and an end wall  113  connecting the first and second sidewalls  111  and  112 . The first sidewall  111  and the second sidewall  112  are substantially parallel to the projection lens module  20 . The end wall  113  is substantially perpendicular to the optical axis of the projection lens module  20 . The casing  11  defines three receiving holes  114  for receiving the three light-source units  12 . Two of the three receiving holes  114  are defined on the second sidewall  112 , and the other receiving hole  114  is defined on the end wall  1   13 . 
     The structures of the three light-source units  12  are substantially the same. Each light-source unit  12  includes a light source  121 , at least one converging lens, and at least one spacer. In the present embodiment, each light-source unit  12  has two converging lenses including a first lens  122  and a second lens  123 , and two spacers including a first spacer  124  and a second spacer  125 . The light source  121 , the first spacer  124 , the first lens  122 , the second spacer  125 , and the second lens  123  are arranged along the optical path of the light emitted from the light source  121  in sequence. The total length of the light-source unit  12  is substantially equal to the depth of the corresponding receiving hole  114 . 
     In the present embodiment, the three light sources  121  of the three light-source units  12  are a red light emitting diode (LED) light source, a blue LED light source, and a green LED light source, respectively. Each light source includes a driving circuit board  121   a  and a LED array (not visible) mounted on a surface of the driving circuit board  121   a  facing the first lens  122 . The LED array is substantially located at the center of the driving circuit board  121   a.    
     The outer diameters of the first spacer  124 , the first lens  122 , the second spacer  125 , and the second lens  123  are substantially the same or equal to the diameter of the corresponding receiving hole  114 . The first spacer  124  and the second spacer  125  are ring-shaped. The inner diameter of the first spacer  124  is bigger than the diameter of the LED array, so that, the first spacer  124  is in direct contact with the driving circuit board  121   a  with the LED array surrounded therein. The driving circuit board  121   a  can be secured to the casing  11  directly to fix the light source  121 . 
     In the present embodiment, the light-source module  10  further includes three support boards  13 . Each driving circuit board  121   a  can be mounted on a support board  13 . In the present embodiment, each support board  13  defines a number of through holes  131 , and the casing  11  defines a number of screw holes  115  corresponding to the through holes  131 . A number of screws  132  are used for securing the support boards  13  to the casing  11 . 
     While assembling the light-source module  10 , the second lens  123 , the second spacer  125 , the first lens  122 , the first spacer  124 , and the light source  121  can be pressed into the receiving hole  114  in sequence, and then secure the driving circuit board  121   a  of the light source  121  to the casing  11 , thus, the second lens  123 , the second spacer  125 , the first lens  122 , the first spacer  124  will be fixed due to pressure of two adjacent elements. The light-source module  10  can be assembled easily. 
     While certain embodiments have been described and exemplified above, various other embodiments will be apparent to those skilled in the art from the foregoing disclosure. The present invention is not limited to the particular embodiments described and exemplified, and the embodiments are capable of considerable variation and modification without departure from the scope of the appended claims.