1.  Field of the Invention
The invention relates to a lens-adjusting module.  More particularly, the invention relates to a lens-adjusting module applied to a projector. 
2.  Description of the Related Art
The design and disposition of the elements inside a projector is closely related to the quality of image projected by the projector.  Lens-adjusting modules of projectors are disclosed in many patents.  For example, a kind of lens-adjusting module of a projector is disclosed in FIGS.  15 to 23 of the US patent No.  20070058133.  Another kind of lens-adjusting module in the present industry is described in the following. 
FIG.  1 is a schematic view of a conventional projector.  FIG.  2 is a schematic view of the lens-adjusting module of FIG.  1.  Referring to FIGS.  1 and 2, the conventional projector P1 includes a lens-adjusting module 100, a light valve 200, an illumination module 300, and a cover 400.  The illumination module 300 disposed inside the cover 400 generates an illumination beam 310.  The light valve 200 is disposed in the cover 400 and located in the transmission path of the illumination beam 310.  The light valve 200 converts the illumination beam 310 into an image beam 210.  The lens-adjusting module 100 is disposed in the cover 400 and a lens 170 of the lens-adjusting module 100 is located in the transmission path of the image beam 210 to project the image beam 210 to a screen (not shown). 
Referring to FIG.  2, the lens-adjusting module 100 further includes a base 120, two first guiding shaft 130, a first adjusting stand 140, two second guiding shaft 150, and a second adjusting stand 160 besides the lens 170.  The first guiding shafts 130 are disposed at the two opposite sides of the base 120 respectively.  The first adjusting stand 140 is installed on the first guiding shafts 130.  The second guiding shafts 150 are disposed at the two opposite sides of the first adjusting stand 140.  The second adjusting stand 160 is installed on the second guiding shafts 150.  Each of the first guiding shafts 130 extends along a first axis A1.  Each of the second guiding shafts 150 extends along a second axis A2.  The first axis A1 is perpendicular to the second axis A2. 
The lens 170 is disposed on the second adjusting stand 160.  The second adjusting stand 160 of the lens-adjusting module 100 may move along the second axis A2, and the first adjusting stand 140 may move along the first axis A1 such that the lens 170 is adjusted by means of moving the first adjusting stand 140 and the second adjusting stand 160. 
According to the lens-adjusting module 100, adjusting the lens 170 is achieved by means of the arrangement of the guiding shafts 130 and 150 and the adjusting stands 140 and 160.  However, the arrangement of the elements in the lens-adjusting module 100 may not satisfy another designer having another requirement of space planning for inside of another projector. 
In addition, because the guiding shafts 130 and 150 and the first adjusting stand 140 are all disposed between the base 120 and the second adjusting stand 160, the cumulative tolerance between the second adjusting stand 160 and the base 120 is relatively large after the lens-adjusting module 100 is assembled.  Accordingly, the predetermined interval between the second adjusting stand 160 and the base 120 is adversely affected by the cumulative tolerance such that an image projected by the lens 170 disposed at the second adjusting stand 160 is out of focus.