Abstract:
A light source mounting apparatus for liquid crystal projector comprises a lamp base (for holding the light generator) and a casing (for shielding light scattering). The lamp base has a board shape holding unit. The casing has a front positioning plane and a strip spring located above the front positioning plane. When the lamp base and casing is reassembled, the holding unit forces the light generator mounted thereon contact tightly the front positioning plane to rapidly complete initial positioning, and the rear end of the strip spring engages the light generator securely for pressing the light generator against the front reference plane tightly without flipping thereby to attain accurate positioning quickly.

Description:
FIELD OF THE INVENTION 
     This invention relates to a light source mounting apparatus for use in liquid crystal projector. 
     BACKGROUND OF THE INVENTION 
     Liquid crystal projector is an image displaying technique well known in the art. Its general operation principle is illustrated in FIG. 1. A light generator  10  has a lamp located in a reflector  11  (which contains a parabolic reflection mirror) to generate reflecting parallel light rays passing through a illumination system  80 , a liquid crystal display panel  40  and a recombination system  90 , and a lens  50  to project the original image from the liquid crystal display panel  40  to a front screen  60 . 
     When there is a need to replace the lamp, the light generator  10  must be taken out or restored through a light source mounting apparatus (referring to FIGS.  2  and  3 ). For instance, the liquid crystal projector made by Epson Co. of Japan has a light source mounting apparatus which includes a steel wire  71  engaged with the outer side of the light generator  10  to couple the light generator  10  with a lamp frame  70 . Then the lamp frame  70  and light generator  10  are mounted in a casing  30  to complete the assembly. For disassembly, the first step is to move a handle  231  to disengage the assembly of the lamp frame  70  and light generator  10  from the casing  30 . Such a design has problems in use, notably: 
     1. When to mount the light generator  10  on the lamp frame  70 , it takes a great force from the user to engage the steel wire  71  with the light generator  10 . Of course, when to replace the light generator  10 , the steel wire  71  also has to be removed. It gives user similar difficulty. 
     2. When to reassemble, such a structure is not able to guide the light generator  10  accurately returning to its original optical path before the disassembly. 
     As every assembly step will create a tolerance, the accumulated tolerance tends to produce a large deviation from the original optical path and will result in project color shift, non-uniformity and decreasing of light intensity. 
     3. When to replace the lamp, the handle  231  has to be pulled with a great force to remove the assembly of the lamp frame  70  and light generator  10  from the casing  30 . Due to the tightly engagement of the power supply plug, the pulling of the handle  231  could easily deform the handle  231  and makes it detached from the lamp frame  70 . From operation perspective, when the handle  231  is not use, it relies the deforming elastic force of the handle  231  to dispose it flatly at the bottom of the lamp frame, therefore will result in a complicated shape and takes more space. It is obviously that there are still rooms for improvement. 
     SUMMARY OF THE INVENTION 
     The primary object of this invention is to provide a light source mounting apparatus for liquid crystal projector that enables the light generator automatically positioning precisely when it is disassembled and reassembled again to ensure the projecting light returning to its original designed optical path. 
     The light source mounting apparatus according to this invention comprises a lamp base and a casing. The lamp base is a board including a holding unit. The casing provides a space for housing at least the lamp base, a front positioning plane and a strip spring located at the front positioning plane. When the whole structure has been disassembled and reassembled again, the holding unit forces the light generator located thereon automatically pressing against the front positioning plane for rapidly finishing the initial positioning, and the strip spring has a rear end to engage with the light generator tightly when the two elements are coupled together such that the light generator will press against the front positioning plane tightly to automatically finish positioning thereby to return the optical path in coincidence with the one prior to the disassembly. 
     The foregoing and additional objects, features and advantages of the present invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic view of a liquid crystal projector. 
     FIG. 2 is an exploded view of a conventional light source mounting apparatus for liquid crystal projector. 
     FIG. 3 is a perspective view of a conventional light source mounting apparatus for liquid crystal projector. 
     FIG. 4 is an exploded view of this invention. 
     FIG. 5 is a perspective view of this invention, showing a lamp base coupled with a light generator. 
     FIG. 6 is another perspective view of the lamp base of this invention. 
     FIGS. 7A through 7D are schematic views of this invention, showing the lamp base coupling with the casing, and the relationship between the strip spring and the reflector. 
     FIG. 8 is a perspective view of this invention. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 4, the light source mounting apparatus according to one embodiment of the present invention consists of a light generator  10 , a lamp base  20  and a casing  30 . When assembling, couple the light generator  10  and lamp base  20  to form a subassembly, then mount the subassembly in the casing  30 . 
     The light generator  10  includes a lamp (not shown in the drawing), a reflector  11  and a power cord  12 . The lamp emits light required for projection. The reflector  11  reflects light emitted from the lamp to become parallel light beam for projecting outwards. The power cord  12  connects to the lamp through the rear end of the reflector  11  and links to a power supply to provide electricity needed for the lamp. 
     The lamp base  20  is substantially a board type member for holding the light generator  10  and includes a power supply bracket  21 , a holding unit  22  and a handle assembly  23 . The bracket  21  and holding unit  22  are located respectively at two ends of one side of the lamp base  20 , and the handle assembly  23  is located at another side of the lamp base  20 . 
     The power supply bracket  21  has a screw bore  211  for fastening the plug of the power cord  12 . 
     Referring to FIGS. 4,  5  and  6 , the holding unit  22  is located at one end of the lamp base  20  opposite to the bracket  21 , and includes a guiding block  221 , a compression spring  222 , a retaining ring  223 , a slide rod  224  and an anchor block  225  for holding the reflector  11 . The guiding block  221  is located at an edge of the lamp base  20  and has a chamfered edge facing another end of the lamp base  20 . The anchor block  225  is also located at the edge of the lamp base  20  and is opposite to the slide rod  224 . The compression spring  222  (or a compressible elastic element or the like) surrounds the slide rod  224  and has two ends making contact respectively with the juncture of the slide rod  224  and lamp base  20  (i.e. at the root portion of the slide rod  224 ) and the retaining ring  223 , and is restricted at two ends for storing or releasing power. The retaining ring  223  is substantially a frame having a center for the rear end of the reflector  11  to wedge therein. One side of the retaining ring  223  is a flat surface (the one contacts the anchor block  225 , i.e. the side contacts the reflector  11  when the reflector  11  is fixedly mounted on the holding unit  22 ). There is a through bore  2231  located at the lower section of the retaining ring  223  mating against the slide rod  224  (at only one dimension) for limiting the movement of the retaining ring  223 . 
     Referring to FIG. 5 for initial mounting of the light generator  10 , press the retaining ring  223  against the compression spring  222  for storing power and move the power cord  12  through the center of the retaining ring  223 ; dispose the reflector  11  between the retaining ring  223  and anchor block  225 ; release the retaining ring  223  so that the retaining ring  223  will push the reflector  11  forwards to the anchor block  225  such that the flat surface of the retaining ring  223  contacted tightly against a flat surface of the light generator  10  (the reflector  11  is clamped by the anchor block  225  and retaining ring  223  because of the releasing power of the compressing spring  222 , and is undergoing the positioning process) for holding the reflector  11  securely. 
     The plug of the power cord  12 , after passing through the guiding block  221 , may be disposed on the power supply bracket  21  and be fastened in the screw bore  211  by means of a screw; and use the edge of one end of the screw to limit the plug in the juncture of the bracket  21  to hold the plug securely on the bracket  21  (of course the bracket  21  is designed in compatible with the bottom end of the plug for aforesaid fastening). 
     Referring to FIGS. 4,  5 , and  6 , the handle assembly  23  includes a handle  231 , a slide plate  232 , a coupling element  233 , a screw  234 , a through hole  235  and an opening  236  for moving the lamp base  20  outwards from the casing  30 . The handle  231  has two substantially vertical sections  2311  and a horizontal section  2312  bridged the two vertical sections  2311  at one end thereof. Another two ends of the vertical sections  2311  being bent vertically against the vertical section  2311  to form engaging ends  2313  pointing toward each other at the plane of the lamp base  20 . The horizontal section  2312  forms a snap section  2314  formed thereon. The slide plate  232  is substantially made of a flat strip having a bulged section  2322  and an aperture  2321  at one end thereof. The coupling element  233  may be an E-type washer or a closed washer for clipping the screw thread of the screw  234 . The through hole  235  is formed by a first groove  2351  and a second groove  2352  normal to each other (of course, they may be in the form of a “” or “L” shape as shown in the drawings), and are located at the center portion of the lamp base  20  (in parallel respectively with the two vertical edges of the lamp base  20 ). The opening  236  has a form mating against the snap section  2314  for engaging with the same, and is located at another end of the lamp base  20 . The through hole  235  and opening  236  are mating against the handle  231  for pulling and holding the handle  231 . 
     To assemble the handle assembly  23 , dispose the engaging ends  2313  through the second groove  2352  and align the bulged section  2322  with the first groove  2351  to place the slide plate  232  in the through hole  235 , and dispose the engaging ends  2313  in the bulged section  2322 , then fasten the screw  234  through the aperture  2321 , and engage the coupling element  233  at the screw thread of the screw  234  adjacent the slide plate  232  to complete the handle assembly  23 . When to store the handle  231 , dispose the snap section  2314  in the opening  236  and push the handle  231  forwards, the snap section  2314  may be engaged to the lamp base  20 , then fasten the screw  234  to the screw bore of the casing for storing the handle  231 . 
     Referring to FIG. 4, the casing  30  and lamp base  20  form a housing space to contain at least the power supply bracket  21 , holding unit  22  and handle assembly  23 . The casing  30  has one side formed a front reference plane  31  and has a strip spring  32  for positioning the reflector  11  and preventing the reflector  11  from flipping backward. The front reference plane  31  is a frame which allows the optical path of the light generator  10  to pass through. The side edges of the frame form a surrounding area which is larger than the external size of the reflector  11 , and has a flat inner surface to serve as the basis of vertical positioning for the reflector  11 . It further has a recess  311  mating against the guiding block  221 . The strip spring  32  has one end extended outwards and formed a “&lt;” shaped pendant in the casing  30  and another end has a screw bore. The strip spring  32  is located above the front reference plane  31 . When the casing  30  engage with the subassembly of the lamp base  20  and light generator  10 , the extended end of the strip spring  32  contacts the retaining ring  223  thereby the reflector  11  will be restricted by the retaining ring  223 , strip spring  32  and front reference plane  31  without moving (as the bottom of the retaining ring  223  is restricted by the compression spring  222 , the strip spring  32  must be located at the upper side to limit the movement of the reflector  11 ). The apertures  33  are formed at selected locations of the casing  30  for dissipating heat generated by the light generator  10  when in use to avoid harmful impact on projection effect. 
     Referring to FIGS. 7A through 7D, the light generator  10  is mounted on the lamp base  20  to reach an initial positioning, then the subassembly of the generator  10  and lamp base  20  is disposed in the casing  30 . At this stage, one end of the front reference plane  31  can be automatically slid to a desired location for positioning through the chamfered edge of the guiding block  221  (as shown in FIG.  8 ), and the recess  311  will match with the guiding block  221 , and the anchor block  225  will be moved away from one side of the reflector  11 . Moreover, the strip spring  32  will engage the rear end of the reflector  11 , and along with the retaining ring  223  to give the reflector  11  a positioning effect. When there is a need to change the lamp, the subassembly of the light generator  10  and lamp base  20  may be taken out from the casing  30  by moving the handle  231  from the opening  236  and pulling the handle  231  outwards. The construction of this invention set forth above may achieve the following effects: 
     1. The apparatus of this invention can reduce the accumulated tolerance resulting from combination of different parts and increase positioning accuracy thereby can prevent color shift, non-uniformity and decreasing of light intensity. 
     2. Disassembly of the parts is very simple and easy. Reassembling of the apparatus does not decrease repositioning accuracy, thus does not need repeated adjustment of the light generator position. The handle of this invention is securely built and will not be broken away when in use. It also takes a smaller space and is more convenient to use. 
     3. The components and construction of this invention do not demand very accurate tolerance, hence fabrication is simpler and costs less. 
     While the preferred embodiment of the invention has been set forth for purpose of disclosure, modifications of the disclosed embodiment of the invention as well as other embodiments thereof may occur to those skilled in the art. Accordingly, the appended claims are intended to cover all embodiments which do not depart from the spirit and scope of the invention.