Abstract:
An exemplary backlight module ( 20 ) includes a light source ( 23 ), a light guide plate ( 21 ), a light source reflector ( 22 ), and a holding device ( 24 ). The light guide plate includes a light incident surface ( 211 ). The light source is disposed adjacent to the light incident surface. The light source reflector attaches to the light guide plate, and includes a fixing hole ( 224 ). The holding device engages with the light source reflector at the fixing hole and restrains the light source in position a predetermined maximum distance away from the light source reflector.

Description:
FIELD OF THE INVENTION 
     The present invention relates to a backlight module having a holding device which is used to hold a light source to a light source reflector of the backlight module. 
     GENERAL BACKGROUND 
     Liquid crystal displays are commonly used as display devices for compact electronic apparatuses. This is because they not only provide good quality images with little power consumption, but also they are very thin. The liquid crystal in a liquid crystal display cannot emit light itself. The liquid crystal needs be lit by a light source, so as to clearly and sharply display text and images. Thus, a backlight module for an LCD is generally needed. 
     Referring to  FIG. 5 , a typical backlight module  10  includes a light guide plate  14 , a reflector  11 , two lamps  12 , and at least one figure of eight-shaped ring  13 . The light guide plate  13  includes a light incident surface  141 , a light emitting surface  142 , and a bottom surface  143 . The light incident surface  141  is perpendicular to both the light emitting surface  142  and the bottom surface  143 . The bottom surface  143  is parallel to the light emitting surface  143 . The reflector  11  includes a side wall  111  and two arms  112 ,  113 . The two arms  112 ,  113  perpendicularly extend from the side wall  111  in a same direction. The two arms  112 ,  113  abut an end portion (not labeled) of the light emitting surface  142  and an end portion (not labeled) of the bottom surface  143  respectively, thereby defining a space  15  between the light incident surface  141  and the reflector  11 . The lamps  12  are received in the space  15 , in order to provide light beams to the light incident surface  141  of the light guide plate  14 . The lamps  12  are linear and are parallel to each other. The figure of eight-shaped ring  13  is used to fix the two lamps  12 . End portions (not shown) of the lamps  12  are fixed with rubber caps (not shown). The lamps  12  are typically cold cathode fluorescent lamps (CCFLs). 
     Some modern liquid crystal displays, such as liquid crystal display televisions, are being made very large. Correspondingly, these liquid crystal displays require long lamps  12 . However, long lamps  12  are liable to bend. In addition, the lamps  12  are particularly susceptible to breakage when subjected to shock. Furthermore, if the lamps  12  bend toward the light incident surface  141  and touch the light guide plate  14 , the backlight module  10  is liable to produce a white-dot phenomenon. That is, the quality of light output by the backlight module  10  is impaired. 
     What is needed, therefore, is a backlight module that can overcome the above-described deficiencies. 
     SUMMARY 
     In one preferred embodiment, a backlight module includes a light source, a light guide plate, a light source reflector, and a holding device. The light guide plate includes a light incident surface. The light source is disposed adjacent to the light incident surface. The light source reflector attaches to the light guide plate, and includes a fixing hole. The holding device engages with the light source reflector at the fixing hole and restrains the light source in position a predetermined maximum distance away from the light source reflector. 
     Other novel features and advantages of the present backlight module will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings. In the drawings, all the views are schematic. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a cross-sectional view of part of a backlight module according to a first embodiment of the present invention, the backlight module including a holding device. 
         FIG. 2  is an isometric view of the holding device of  FIG. 1 . 
         FIG. 3  is a cross-sectional view of part of a backlight module according to a second embodiment of the present invention. 
         FIG. 4  is an isometric view of a pair of holding devices of a backlight module according to a third embodiment of the present invention. 
         FIG. 5  is a cross-sectional view of part of a conventional backlight module. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     Reference will now be made to the drawing figures to describe various embodiments of the present invention in detail. 
     Referring to  FIG. 1 , a backlight module  20  according to a first embodiment of the present invention includes a light guide plate  21 , a reflector  22 , two lamps  23 , and a holding device  24 . The light guide plate  21  includes a top light emitting surface  212 , a light incident surface  211  adjacent and perpendicular to the light emitting surface  212 , and a bottom surface  213 . The reflector  22  includes a side wall  221  and two arms  222 ,  223 . The two arms  222 ,  223  perpendicularly extend from the side wall  221  in a same direction. The side wall  221  includes a rectangular fixing hole  224  in a center thereof. The two arms  222 ,  223  abut an end portion (not labeled) of the light emitting surface  212  and an end portion (not labeled) of the bottom surface  213  respectively, thereby defining a space  25  between the light incident surface  211  and the reflector  22 . The lamps  23  are received in the space  25  in order to provide light beams to the light incident surface  211  of the light guide plate  21 . The holding device  24  is engaged in the fixing hole  224 , and thereby fixes the lamps  23  to the reflector  22 . The two lamps  23  are linear, and are parallel to each other. End portions of the lamps  23  are fixed with rubber caps (not shown). The lamps  23  are typically cold cathode fluorescent lamps (CCFLs). 
     Referring also to  FIG. 2 , the holding device  24  includes a U-shaped fixing portion  241  and a holding portion  245 . The holding portion  245  is integrally connected to a base body (not labeled) of the fixing portion  241 . The fixing portion  241  is used to fix the holding device  24  to the side wall  221  of the reflector  22 . The holding portion  245  is used to prevent the lamps  23  from bending toward the light guide plate  21 . 
     The fixing portion  241  includes a first fixing arm  242  and a second fixing arm  243  parallel to each other. The first fixing arm  242  includes a first protrusion  2421  extending from an end portion thereof, and a first block  2422  extending from a middle portion thereof. The second fixing arm  243  includes a second protrusion  2431  extending from an end portion thereof, and a second block  2432  extending from a middle portion thereof. The first protrusion  2421  and the second protrusion  2431  extend perpendicularly from end portions of the first fixing arm  242  and the second fixing arm  243  in opposite directions. The first block  2422  and the second block  2432  extend perpendicularly from middle portions of the first fixing arm  242  and the second fixing arm  243 , but in opposite directions. The first protrusion  2421  is perpendicular to the first block  2422 . The second protrusion  2431  is perpendicular to the second block  2432 . The first fixing arm  242  and the second fixing arm  243  are flexible, and can be made from transparent resin such as polymethyl methacrylate (PMMA) or polycarbonate (PC). That is, the entire holding device  24  can be molded as a single piece of PMMA or PC. 
     A minimum distance between the first fixing arm  242  and the second fixing arm  243  is approximately equal to a width of the fixing hole  224  of the reflector  22 . A minimum distance between the first protrusion  2421  and the first block  2422  is approximately equal to a thickness of the side wall  221  of the reflector  22 . A minimum distance between the second protrusion  2431  and the second block  2432  is also approximately equal to the thickness of the side wall  221 . 
     The holding portion  245  includes a first holding arm  2451  and a second holding arm  2452 . The first holding arm  2451  and the second holding arm  2452  extend downwardly and bend outwardly from the base body of the fixing portion  241 . Cross-sections of the first holding arm  2451  and the second holding arm  2452  are substantially semicircular. Open sides of the first holding arm  2451  and the second holding arm  2452  generally face along a same direction in which the fixing arms  242 ,  243  extend from the base body. A diameter of the semicircles is approximately equal to a diameter of the lamps  23 . 
     In assembly of the backlight module  20 , the first fixing arm  242  and the second fixing arm  243  of the holding device  24  are inserted into the fixing hole  224 . The first and second fixing arms  242 ,  243  elastically deform when the protrusions  2421 ,  2431  pass through the fixing hole  224 , and then rebound. Thus the protrusions  2421 ,  2431  and the blocks  2422 ,  2432  cooperatively clip the side wall  221  and hold the holding device  24  in place. The lamps  23  are held by the holding arms  2452 ,  2451 , so that the lamps  23  cannot bend toward the light incident surface  211  of the light guide plate  21 . Consequently, a white-dot phenomenon is prevented from occurring. Furthermore, the lamps  23  are buffered by the various parts of the holding device  24 , and are therefore less prone to break when the backlight module  20  is subjected to shock or vibration. 
     Referring to  FIG. 3 , a backlight module  30  according to a second embodiment of the present invention is similar to the backlight module  20 . However, cross-sections of holding arms  341  of a holding device  34  are circular. Lamps (not labeled) can be fixed firmly, and the reliability of the backlight module  30  is enhanced. 
     Referring to  FIG. 4 , a backlight module  40  according to a third embodiment of the present invention is similar to the backlight module  20 . However, the backlight module  40  includes a first holding device  44  and a second holding device  45 . Correspondingly, a side wall (not shown) of a reflector (not shown) includes two fixing holes (not shown) to enable fixing of the two holding devices  44 ,  45  thereto. Open sides of two holding arms (not labeled) of the first holding device  44  generally face along a same direction in which fixing arms (not labeled) extend from a base body of the first holding device  44 . Open sides of two holding arms (not labeled) of the second holding device  45  generally face along an opposite direction to a direction in which fixing arms (not labeled) extend from a base body of the second holding device  45 . Lamps (not labeled) can be fixed firmly by the two holding devices  44 ,  45  in cooperation. 
     It is to be understood, however, that even though numerous characteristics and advantages of the present embodiments have been set out in the foregoing description, together with details of the structures and functions of the embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in matters of shape, size, and arrangement of parts within the principles of the invention to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.