Abstract:
A backlight module has an upper frame and a lower frame engaged mutually for forming a receiving cavity therein, of which the upper frame has a stop base and is arranged at its top with a support sheet protruding inwardly along an inner perimeter thereof. A light-guide plate and a lighting member are arranged between the upper and lower frames, and a group of optical members is right on the support sheet in order to make the light from the lighting member via the light-guide platestop base uniform and to avoid the light being dissipated directly therefrom. Furthermore, the module is coupled with a substrate positioned on the stop base and over the optical members. The product thereby is easily and smoothly assembled. The group of optical members are conveniently checked, and the upper and lower frames are easily disassembled from each other if examination is necessary.

Description:
This Application is a Continuation-in-Part of application Ser. No. 10/857,383, filed 28 May 2004 now abandoned, and entitled backlight module. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to a backlight module, and particularly to a backlight module that is easy for sequential procedures, including assembly, quality examination and disassembly. 
     2. Description of the Prior Art 
     Generally, a backlight module refers to a device member capable of providing a light source from the back of a product, which has been widely used in various products related to information, communication and consumer goods, such as liquid crystal displays (LCD), film scanners, slide projectors and so on. The backlight module mainly includes an incident light source, a light-guide plate, a diffusion sheet, a prism sheet and a brightness enhancement film (BEF). Put simply, its principle is that a self- luminous light from a light source, for example, a cold cathode fluorescent lamp (CCFL) and a lighting diode (LED), is conducted in by a light-guide plate to produce an even surface light source. Meanwhile, to keep the products competitive in future markets, the backlight module needs to take several product evolution directions into account: lighter weight, miniaturization, lower power consumption, higher brightness and lower cost. 
     Reference is made to  FIG. 1 , which is an assembly diagram of a conventional backlight module  1   a . The module  1   a  includes an upper frame  10   a  and a lower frame  11   a , which are engaged with each other and form a receiving cavity therebetween, and further a light-guide plate  12   a , lighting member  13   a , a reflective sheet  14   a , at least one diffusion sheet  15   a  and at least one prism sheet  16   a , all of which are received within the receiving cavity. The semi-finished module will be further coupled with a glass substrate  2   a . The upper frame  10   a  is provided with a perimetric stop base  101   a  that is arranged to protrude inward along the inner perimeter at the top side of the frame  10   a . During assembly of the module, the upper frame  10   a  is upside down with respect to  FIG. 1 , while the perimetric stop base  101   a  is located beneath the upper frame  10   a . According to the design requirement, the diffusion sheet  15   a  and the prism sheet  16   a  are placed in order on the perimetric stop base  101   a . After the light-guide plate  12   a  and the lighting member  13   a  are mounted, the reflective sheet  14   a  is laid on the light-guide plate  12   a . The lower frame  11   a  and the upper frame  10   a  are then engaged for the purpose of securing the light-guide plate  12   a  and the lighting member  13   a . At this time, the semi-finished product is roughly assembled. The semi-finished product is then put upside down, such that the perimetric stop base  101   a  is located above the light-guide plate  12   a . The glass substrate  2   a  is mounted on the perimetric stop base  101   a , allowing the glass substrate  2   a  in connection with the diffusion sheet  15   a , the prism sheet  16   a , the light-guide plate  12   a , the lighting member  13   a  and the reflective sheet  14   a  to be arranged opposite the perimetric stop base  101   a.    
     However, during assembly of the conventional backlight module  1   a , a step of turning over the upper frame  10   a  is required, and it is thus obvious that the assembly process is not smooth. Furthermore, the lower frame  11   a  and the upper frame  10   a  are arranged with a mutual securing engagement structure. After the lower frame  11   a  is engaged and secured with the upper frame  10   a , it is difficult to disassemble, which is disadvantageous to the improvement of production efficiency. If there is any need for maintenance and repair or if replacement of the diffusion sheet  15   a  or the prism sheet  16   a  becomes necessary, the rework process is bothersome to operators and the products are prone to damage. Therefore, some hazards of low product yield may occur while the structure is disadvantageous and could result in disfigurement or damage. The above-mentioned product damage includes scores and scratches on the diffusion sheet  15   a , the prism sheet  16   a , the light-guide plate  12   a  and the reflective sheet  14   a , which adversely affect the overall brilliancy, thus reducing the value of the products. Moreover, depending on different design requirements, the quantity of the diffusion sheets  15   a  and the prism sheets  16   a  may not be the same, and neither the assembling sequence of the diffusion sheets  15   a  and the prism sheets  16   a  to be assembled is. In the event that a polarizing sheet, an intensifier sheet and other members are added for purpose of adaptation of further optical characteristic, and it is desired to perform a test process to verify the members are assembled in the right sequence and registered properly, similar problems occur during said test process. Dissassembly of the engaged lower frame  11   a  and upper frame  10   a  is difficult, and the products are potentially damaged during disassembly and reassembly of the members. Additionally, in the assembled structure of the conventional backlight module  1   a , the stop base  101   a  is arranged over the optical films; thus the upward and even light output obtained from the effect of those optical films is subject to reduced light output area due to blocking by the stop base  101   a . The conventional backlight module  1   a  is unable to be made more economically. 
     Accordingly, this invention is provided to remove the above disadvantages with a reasonable design. 
     SUMMARY OF THE INVENTION 
     The main object of the invention is to provide a backlight module, which can reduce turnover steps, allowing the products to be easily and smoothly assembled and improves production efficiency to further reduce production costs. 
     Another object of the invention is to provide a backlight module, which allows convenient checking that the module is properly assembled. The module is additionally easily repaired, further improving assembly efficiency and reducing labor wastes. 
     Yet another object of the invention is to provide a backlight module, which can avoid product damage during disassembly of the engaged upper and lower frames and eliminate defect possibility to reduce further production costs. 
     Yet another object of the invention is to provide a backlight module, which can increase light availability and a light output area, to achieve efficient utilization of the backlight module. 
     In order to achieve the above object, the present invention provides a backlight module, comprising mutually engaged upper and lower frames, of which the upper frame has a stop base and is arranged at its top with a support sheet protruding inwardly along an inner perimeter thereof. A light-guide plate and a lighting member are arranged between the upper and lower frames. A group of optical members are arranged on the support sheet, and a substrate is arranged on the stop base. The group of optical members is arranged in order to make uniform the light from the lighting member via the light-guide plate and to avoid the light being dissipated directly therefrom, and thereby allow the product to be easily and smoothly assembled. The group of optical members can be conveniently checked. The upper and lower frames are easily disassembled from each other if the examination is necessary. 
     The features and technical contents of the present invention will become apparent from the detailed description of the present invention with reference to the accompanying drawings; the detailed description and drawings are intended to be illustrative and not restrictive. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The foregoing aspects and many of the attendant advantages of this invention will be more readily appreciated as the same becomes better understood by reference to the following detailed description, when taken in conjunction with the accompanying drawings, wherein: 
         FIG. 1  is a diagrammatic illustrating a conventional backlight module; 
         FIG. 2  is a cross dicomposition view illustrating an embodiment of a backlight module according to the present invention; 
         FIG. 2A  is cross dicomposition view to show a raise thin layer of the light-guide plate according to the present invention; 
         FIG. 3  is a cross dicomposition view illustrating another embodiment of the backlight module according to the present invention; 
         FIG. 3A  is an enlarged side view according to  FIG. 3 ; 
         FIG. 4  is a cross dicomposition view illustrating an additional embodiment of the backlight module according to the present invention; 
         FIG. 4A  is an enlarged side view according to  FIG. 4 ; 
         FIG. 5  is a perspective view of the an embodiment of the optical members according to the present invention; 
         FIG. 5A  is a perspective view of the another embodiment of the optical members according to the present invention; 
         FIG. 5B  is an enlarged cross-sectional profile according to  FIG. 5 ; and 
         FIG. 6  is an enlarged perspective view according to  FIG. 5 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 2  illustrates a backlight module  1  according to this invention, comprising a mutually engaged an upper frame  10  and a lower frame  11  for forming a receiving cavity therein. The engagement structure between the upper frame  10  and the lower frame  11  shouldn&#39;t be not limited to the embodiments mentioned below. The upper frame  10  includes a stop base  101 , a support sheet  102  extending horizontally along an inner perimeter of the stop base  101 , and a limit wall  103  extending upwardly from a top surface of the stop base  101 . The support sheet  102  encompasses an inner perimeter of the stop base  101  in order to avoid the light being dissipated directly from a non-overlapping space between the stop base  101  and the optical members  15 ,  50  that the light utility and availability will increase. The backlight module  1  further includes a light-guide plate  12  positioned inside the receiving cavity between the lower frame  11  and the upper frame  10 , a lighting member  13  positioned inside the receiving cavity and adjacent to at least one lateral side of the light-guide plate  12 , a group of optical members  15  arranged right on the support sheet  102  in order to make uniform the light emitted from the lighting member  13  via the light-guide plate  12 ; and a substrate  2  disposed on the stop base  101  and over the optical members  15  and adjacent to the limit wall  103 . In one embodiment, the upper frame  10  and the lower frame  11  can be made of plastic and metal (particularly iron), respectively. The support sheet  102  of the upper frame  10  together with the lower frame  11  forms the receiving cavity, so as to be used to sandwich securely the light-guide plate  12  and the lighting member  13 . The upper frame  10  can be provided such that the size and height of the support sheet  102  can be adjusted, for further facilitating disposal of the light-guide plate  12 . In this embodiment, a reflection member  14  is arranged between the light-guide plate  12  and the lower frame  10  and further extends to cover two lateral sides of the light-guide plate  12 . Otherwise, the reflection member  14  is arranged between the light-guide plate  12  and the lower frame  11 , which may be disposed in the form of a reflection sheet or a reflection film beneath the light-guide plate  12 ; alternatively, the reflection member  14  with reflection capability can be formed by directly plating a reflection layer on the lower surface of the light-guide plate  12 . 
     In particular, due to the existence of the support sheet  102 , a small gap is formed between the light-guide plate  12  and the group of optical members  15 . A thin layer  121 , illustrated in  FIG. 2A , is raised from a top of the light guide plate  12  as an extension of the light-guide plate  12 , so as to fill in the gap and be joined with the group of optical members  15 . 
     Reference is made to  FIG. 3 , the upper frame  10  has a straight wall  104  extending downwardly therefrom and being received in the lower frame  11 . In this embodiment, the limit wall  103  encompasses the upper frame  10  in a continuous manner. In this embodiment, the stop base  101  encompasses the inner perimeter of the upper frame  10 , and the support sheet  102  encompasses an inner perimeter of the stop base  101 . Illustrated in  FIG. 3A , the straight wall  104  has a projection  1041  corresponding to a slot  111  of the lower frame  11  so that the upper frame  10  engages with the lower frame  11 . 
     Reference is made to  FIGS. 4 and 4A , the lower frame  11  has a projection  112  corresponding to a flap  105 , which extends from the upper frame  10  with a slot  1051 , so that the upper frame  10  engages with the lower frame  11 . In this embodiment, the limit wall  103  is arranged discontinuously on at least two corners of the upper frame  10 . 
     Illustrated in  FIGS. 4 ,  5 A,  5 B and  6 , the stop base  101  has a recess  1011  formed on at least one side thereof to define two step portions  1012  and an indentation  1013  between the two step portions  1012  in order to reveal the support sheet  102 . Each of the optical members  15  has a tab  151 , and these tabs  151  may be aligned as illustrated in  FIG. 5A  or not aligned with one another for being received inside the recess  1011 . In  FIG. 5 , the tabs  151  correspond to the indentation  1013  to contact with the revealed surface of the support sheet  102 . Furthermore, an adhesive member  16  can be applied onto the outermost one of the tabs  151  and the two step portions  1012  at the same time, in order to secure the optical members  15  to the upper frame  10  thereby. In  FIG. 5A , the tabs  151  correspond to and contact to the revealed surface of the indentation  1013  and top surfaces of the step portions  1012 , so that these irregular tabs  151  of the optical members  15  are accommodated in the recess  1011  with the indentation. The adhesive tape  16  still can be applied for connecting the optical members  15  to the upper frame  10 . In particular, the support sheet  102  shown in  FIG. 7  can encompass at least one side along an inner perimeter of the stop base  101 , that would achieve similar effects. 
     The lighting member  13  may be a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which may be strip-shaped or L-shaped, and be arranged aside or around the light-guide plate  12 , in order to meet the requirement of nondirectional light output. The group of optical members  15  comprises a diffusion sheet, a prism sheet and so on. Depending on various design requirements, the number and sequence of these diffusion sheets and prism sheets may be configured variably. In order to achieve special optical effects, the group of optical members  15  may further comprise a polarizing sheet, a color filter (CF), brightness enhancement film (BEF), anti-glare film (AG film), anti-reflective film (AR film) and so on, according to specific design requirements. 
     The backlight module according to the embodiment illustrated in  FIG. 2  is assembled in the following steps. The reflection member  14 , the light-guide  12  and the lighting member  13  are directly received into the receiving cavity in the lower frame  11 . The upper frame  10  is then inserted to be jacketed and engaged with the lower frame  11 , so as to sandwich the light-guide plate  12  and lighting member  13  together. The need for a turnover step for the upper frame  10  is eliminated, thereby facilitating the easy and smooth assembly of the module, and thus further speeding production flow and improving production efficiency. Additionally, according to a specific design requirement, the group of optical members  15  are arranged above the stop base  101 , such that the group of optical members  15  and the light-guide plate  12  form a relationship in which they are positioned at opposite sides of the stop base  101 . In particular, a side light source emitted from the lighting member  13  is converted into a surface light source through the light-guide plate  12 . After the light source passes through the stop base  101 , benefiting from the optical effect of the diffusion sheet or the prism sheet in the group of optical members  15 , the projection of the surface light source is not affected by the limit of the stop base  101 , thereby increasing the area of the light output and achieving the efficient utilization of the backlight module  1 . 
     During situations such as, for example, examination, maintenance or material replacement during the production process, the backlight module  1  according to this invention can easily be examined and the constitution and configuration of the group of optical members  15  changed and replaced, without dissassembling the upper frame  10  from the lower frame  11 , thereby improving assembly, the quality of the backlight module  1 , and the entire production efficiency. In addition, without dissassembling the mutually engaged lower frame  11  and upper frame  10 , the risk of unnecessary damage to the products, such as scratches resulting in uneven overall brilliance can be avoided, thereby reducing the manufacturing cost. 
     With respect to the backlight module industry, material costs are a significant portion of the total cost of a backlight module, and some key materials are mainly sourced from only a few Japanese and US manufacturers; the profit margins of backlight module manufacturers therefore rests on assembling charge and other expenses. From the view point of the manufacturing process, a backlight module can be considered to be a labor-intensive assembly industry with high management requirements. Therefore, the backlight module  1  according to the invention features advantages of being easy to assemble and examine and being convenient to maintain. This not only improves the smoothness of the production flow, but also effectively reduces examination and scrap costs; furthermore the efficient utilization of the light output area is improved. The backlight module  1  according to this invention has a great advantage in keeping competitive in the era of profit squeezing. In conclusion, the desired objects and functions are achieved in this invention; while the techniques and means have been disclosed above merely as one of the preferred embodiments of this invention. It is intended that the appended claims cover all such modifications and variations made to these embodiments as fall within the spirit and scope of this present invention.