Abstract:
A vertical-type backlight unit for flat panel display apparatuses. The vertical-type backlight unit includes a plurality of lamps installed in a housing in substantially parallel manner. A plurality of reflection plates are combined with corresponding lamps to constitute independent lamp module cartridges, each of which is removable from one side of the housing. A diffusing pad/plate is disposed over the plurality of lamp module cartridges for diffusing light. An optical sheet is optionally provided on the diffusing pad/plate.

Description:
BACKGROUND OF INVENTION  
         [0001]    1. Field of the Invention  
           [0002]    The present invention relates to a vertical-type backlight unit suited for flat display panels, and more particularly, to a vertical-type backlight unit having a plurality of removable lamp module cartridges.  
           [0003]    2. Description of the Prior Art  
           [0004]    Backlight modules are known as a key component for the liquid crystal displays, which are widely applied to different kinds of products such as digital cameras, notebooks, personal digital assistants (PDAs), mobile phones, vehicle satellite navigation systems, computer monitors, flat panel TVs and so on. Since the liquid crystal displays are passive luminous devices, a back light unit is required for the LCD devices to meet the requirements of night vision and full color imagery. Basically, the back light unit, which is disposed under the display panel, comprises a luminous means and a diffuser for generating light beams and scattering the light beams uniformly to the display panel. According to the position of the luminous means, the back light units are divided into several types, such as the vertical-type back light unit, in which the light source is generated under the display panel, or the edge-type back light unit, in which the light source is projected from the edges. Among all kinds of back light units, since the vertical back light unit generates light beams under the display panel, therefore, the vertical back light units are widely used in large size display panels or those display panels which need high brightness, such as TV sets.  
           [0005]    Referring to FIG. 1, it is a cross-sectional view of a vertical back light module  10  according to the prior art. The vertical back light module  10  is disposed under a display panel  12  and comprises a plurality of lamp tubes  14 , a diffusing plate  16 , and a reflection plate  18 . The lamp tubes  14  are arranged in a close chamber  30  defined by the diffusing plate  16  and the subjacent metal reflection plate  18 . The reflection plate  18  is utilized for upwardly reflecting the light source generated by the lamp tubes  14  and thereby increase the light use efficiency of the back light module  10 . The diffusing plate  16  is employed for scattering the light source to the display panel  12 . Typically, the diffusing plate  16  is made of acrylic or propylene carbonate (PC) having a light transmittance of about 50% to 80%. In some cases, a diffusing sheet  20  and an optical film  22  are disposed over the diffusing plate  16 . Typically, the diffusing sheet  20 , which is made of acrylic or PC, has a higher light transmittance than that of the diffusing plate  16  and has a thickness of about 0.11 mm to 0.15 mm.  
           [0006]    However, the above-described prior art vertical backlight unit  10  has a drawback in that it is time-consuming and very inconvenient to change the lamp tubes. When one of the lamp tubes does not function well or becomes out of order, the users have to carefully remove the display panel  12 , the diffusing sheet  20 , the optical film  22 , and then the diffusing plate  16  from the housing with a screw or other like tools to replace it with a new one. Occasionally, some people abandon the whole liquid crystal display device that only has one or two lamp tubes out of order because they don″t know how to change the lamp tubes. In light of the foregoing, it becomes apparent that there is a need for an improved vertical backlight unit module that is convenient for the users to change lamp tubes when some of which are out of order.  
         SUMMARY OF INVENTION  
         [0007]    It is therefore one object of the present invention to provide a vertical type backlight unit having a plurality of independent lamp module cartridges, each of which is removable from one side of the LCD housing.  
           [0008]    According to one preferred embodiment of the present invention, a vertical-type backlight unit comprises a plurality of lamp tubes arranged in parallel within a housing, a plurality of reflection plates disposed underneath each of the plurality of lamp tubes and each of the reflection plates being integrated with corresponding lamp tubes to constitute an independent lamp module cartridge, which is removable from one side of the housing, and a diffusing plate disposed over the plurality of lamp tubes and fixed on the housing, the diffusing plate being used to scattering the light generated by the plurality of lamp tubes.  
           [0009]    It is advantageous to use the present invention because users can easily change a broken lamp tube directly from one side of the panel housing manually. The present invention provides time-effective and convenient lamp tube changing mechanism. The users don″t even need a screw or other tools to change the lamp tubes.  
           [0010]    Other objects, advantages, and features of the present invention will become more clearly and readily apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
       
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]    [0011]FIG. 1 is a cross-sectional view of a vertical back light module according to the prior art;  
         [0012]    [0012]FIG. 2 is a cross-sectional view showing the backlight unit according to the first preferred embodiment of the present invention;  
         [0013]    [0013]FIG. 3 is a schematic oblique view showing a single lamp module cartridge of FIG. 2 according to the first preferred embodiment of the present invention;  
         [0014]    [0014]FIG. 4 is schematic cross-sectional view showing a vertical backlight unit according to the second preferred embodiment of the present invention; and  
         [0015]    [0015]FIG. 5 is a schematic diagram showing the independent lamp module according to the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0016]    [0016]FIG. 2 is a cross-sectional view showing the backlight unit  50  according to the first preferred embodiment of the present invention. FIG. 3 is a schematic oblique view showing a single lamp module cartridge of FIG. 2 according to the first preferred embodiment of the present invention. As shown in FIG. 2, a vertical backlight unit  50  is installed underneath a flat panel  60  such as an LCD flat panel. The backlight unit  50  comprises a housing  54 , a diffusing pad or diffusing plate  51  fixed on the housing  54 , a plurality of reflection slots  52 , and a plurality of lamp tubes  53  disposed in corresponding reflection slots  52 . Each of the plurality of lamp tubes  53  is integrated with each of corresponding reflection slots  52  constitute a lamp module cartridge, as indicated in FIG. 3. The lamp module cartridge can be removed or changed independently from one side of the housing  54  without the need of removing the flat panel or reflection optical components. The reflection slot plates  52  are made of U-shaped metal plates having similar size. A through hole  521  is located in the metal plate for accommodating a wiring line (not shown).  
         [0017]    The lamp tubes  53  may be cold cathode fluorescent lamps (CCFL) arranged in corresponding chambers defined by the diffusing plate  51  and the plurality of reflection slot plates  52 . Each of the reflection slot plates  52  has a flat bottom surface and two oblique reflection walls. Preferably, the reflection slot plates  52  are made of aluminum metal or alloys, foamed PET, or PC resins, but not limited thereto. The diffusing plate  51  is made of poly (methyl methacrylate) (PMMA), propylene carbonate, PET polyester, or the like. According to the preferred embodiment of this invention, the diffusing plate  51  is made of PMMA and has a thickness of few millimeters. Optionally, an optic film (not shown) comprising a diffusing sheet, a prism sheet, and a polarization transmission/reflection sheet may be disposed on the top of the diffusing plate  51 .  
         [0018]    Referring to FIG. 4, it is a schematic cross-sectional view showing a vertical backlight unit  70  according to the second preferred embodiment of the present invention. FIG. 5 is a schematic diagram showing the independent lamp module according to the present invention. As shown in FIG. 4, likewise, the vertical backlight unit  70  is installed underneath the flat panel  80 . The backlight unit  70  comprises a housing  74 , a diffusing plate  71  fixed on the housing  74 , a flat reflection plate  72 , and a plurality of lamp tubes  73  arranged in parallel manner between the reflection plate  72  and the diffusing plate  71 . Each of the plurality of lamp tubes  73  is integrated with the housing  74  to become an independent and removable lamp module. The lamp module design enables a user to change lamp tubes that are out of order independently from one side of the housing  74  without affect other well functioning lamp tubes. As shown in FIG. 4, the lamp tube  73  has one low-voltage end connected to a first plastic capping piece  75  and one high-voltage end connected to a second plastic capping piece  76 . The first plastic capping piece  75  and the second plastic capping piece  76  may be made of silicon rubber or other silicone-like materials and are removably embedded at opposite sidewalls of the housing  74 . A low-voltage end connector  77  having therein a terminal (not shown) is installed in the first plastic capping piece  75 . The low-voltage end of the lamp tube  73  is electrically connected to the terminal in the low-voltage end connector  77  from the rear side of the first plastic capping piece  75 . A high-voltage end connector  78  is electrically connected to the low-voltage end connector  77  through a first wiring line  79   a . The high-voltage end connector  78  is electrically connected to the high-voltage end of the lamp tube  73  through a second wiring line  79   b.  When the lamp tube  73  is out of order, the user can unplug the low-voltage end connector  77  and disconnect the low-voltage end connector  77  from the low-voltage end of the broken lamp tube  73 . Then, the first and second plastic capping pieces  75  and  76  are removed to change the lamp tube  73 .  
         [0019]    In accordance with the second preferred embodiment of this invention, the lamp tubes  73  may be cold cathode fluorescent lamps (CCFL) arranged in a chamber defined by the diffusing plate  71  and the reflection plate  72 . The reflection plate  72  has a flat bottom surface and is made of aluminum metal or alloys, foamed PET, or PC resins, but not limited thereto. The diffusing plate  71  is made of poly (methyl methacrylate) (PMMA), propylene carbonate, PET polyester, or the like. According to the second preferred embodiment of this invention, the diffusing plate  71  is made of PMMA and has a thickness of few millimeters. Optionally, an optic film  91  and a diffusing sheet  92  may be disposed on the top of the diffusing plate  71 .  
         [0020]    It is advantageous to use the present invention because users can easily change a broken lamp tube directly from one side of the panel housing manually. In addition, the present invention provides time-effective and convenient lamp tube changing mechanism. The users don″t even need a screw or other tools to change the lamp tubes.  
         [0021]    Those skilled in the art will readily observe that numerous modifications and alterations of the present invention method may be made while retaining the teachings of the invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.