Abstract:
A display module includes components of a display panel having an outward first FPC for connecting to a system, wherein the first FPC has a foldable part on which a welding area is defined, and a backlight unit opposite to the display panel for providing illumination for the display panel. The backlight unit has an outward second FPC which is welded with the welding area of the foldable part. Both the foldable part and second FPC are folded and turned around to keep the welding area attach to the backside of the backlight unit.

Description:
RELATED APPLICATIONS 
   This application is a Division of application U.S. Ser. No. 10/968,078, entitled “PLANAR DISPLAY MODULE” and filed on Oct. 20, 2004 now U.S. Pat. No. 7,259,823. 

   FIELD OF THE INVENTION 
   The present invention relates to a planar display module. More particularly, the present invention relates to a design of disposing a connection between a first FPC of a display panel and a second FPC of a backlight unit at the backside of the backlight unit. 
   BACKGROUND OF THE INVENTION 
   A large number of thin film transistors (TFTs), pixel electrodes, and scan lines and data lines across each other are fabricated by processes of depositions, photolithography and etching to form a pixel array on a first glass substrate. In order to provide voltages and signals for activating the TFT in each pixel unit, patterns of electrical circuits are formed on the first glass substrate to electrically connect the pixel array and micro devices on the periphery of the first glass substrate. By this way, timing controller and source drive integrated circuits (ICs) disposed around the first glass substrate and the gate driver IC constructed on the side of the first glass substrate can respectively transmit data signals and scan signals to each pixel unit through the patterns. A color filter and a common electrode layer are formed subsequently on a second glass substrate. In the process of assembling a display panel, the second glass substrate with the color filter and common electrode layer attached thereon is reversed to face the pixel array on the first glass substrate. Thereafter, a liquid crystal (LC) layer is sandwiched between the second and first substrates. 
   Because the LC layer cannot emit lights by itself, a backlight unit is disposed opposite to the display panel to provide light to the liquid crystal display for displaying images. For example, the backlight unit of a small-scale liquid crystal display (LCD) comprises a light-guide plate, films, a reflector and a light emitting diode (LED). The light-guide plate is preferably an acrylic plate made by injection molding. The LED is constructed at a side of the light-guide plate. Lights emitting from the LED enter the light-guide plate through an edge thereof and transmit to another end of the light-guide plate by total internal reflection. The reflector is opposite to the light-guide plate to avoid light leaking from the surface or the light-guide plate. Further, in order to enhance the uniformity of the light illuminating the surface of the light-guide plate, a brightness enhanced film (BEF) and a diffuser are generally constructed upon the light-guide plate, wherein the diffuser is used to diffuse the lights and the BEF is used to focus the lights. 
   Referring to  FIG. 1 , a construction of a display panel  1  and a backlight unit  2  according to the prior art is shown. As described above, the display panel  1  comprises a first glass substrate  10 . On the first glass substrate  10  is a displaying area  11  comprising of a second glass substrate and a liquid crystal layer. A source driver IC  12  and a gate driver IC  13  are respectively mounted on the first glass substrate  10  around the displaying area  11  to control a pixel array within the displaying area  11 . Generally, an extending flexible printed circuit (FPC)  14  is fabricated at the side near the source driver IC  12 . Back-end of the FPC  14  is connected to the source driver IC  12  and the gate driver IC  13  through the circuit layout on the first glass substrate  10 , whereas the front-end of the FPC  14  is connected to the system for transmitting controlling signals thereof to the display panel  1 . 
   It is noted that another extending FPC  21  is mounted on an internal sidewall of a casing of the backlight unit  2  for the purpose of providing power to the LED within the backlight unit  2 . As shown in the figure, the front end of the FPC  21  is connected to the FPC  14  by welding. Thus, the power from the system is transmitted to the LED through the FPC  14 . Now a typical design of the LCD is used as an illustration. A welding area  141  is usually defined on the FPC  14  for the electrical contact of the FPC  21  while assembling the display panel  1  and the backlight unit  2 . 
   It is noted, however, there are serious drawbacks at the electrical contact of the FPC  14  and the FPC  21 . Referring to  FIG. 2 , when the assembling of the display panel  1  and the backlight unit  2  has been accomplished, the assembly will subsequently be accommodated into a casing of a system (e.g. PDA, digital cameras, mobile phones, handheld PC or the like). At this time, the FPC  14  and the FPC  21  are generally folded downward so as to allow the whole assembly to be inserted into the casing of the host system and enable the FPC  14  to be received in a slot, which electrically connect to the interior of the system. Thus, signal connection is built. Under the condition described herein, the welding area  141  on the FPC  14  increases the thickness of the FPC  14 . Accordingly, the difficulty in folding the FPC  14  is elevated while assembling. Further, the FPC  21  easily peels off and separates from the welding area  141  of the FPC  14  when the FPC  14  and the FPC  21  connecting at the welding area  141  are folded and bended simultaneously. 
   In practice, the rate of the short circuit derived from separation between the FPC  14  and FPC  21  is about 5% to 10%. Hence, it is important to seek solutions for solving the problems existing in the present process. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a design in which a welding area for electrically connecting a first FPC of a display panel with a second FPC of a backlight unit is defined on the display panel or on the backside of the backlight unit. 
   In the first embodiment of the present invention, a first display module comprises a first glass substrate with a plurality of TFTs fabricated thereon, an second glass opposite to the first glass substrate and having a color filter adhered thereto, a liquid crystal layer sandwiched between the first and the second glass substrates, a driver. IC mounted on the first glass substrate for driving the TFTs, and a first FPC, wherein back-end of the first FPC is connecting to the driver IC and the front-end is extending outwardly from the first glass substrate for being in contact with a system. The first display module also comprises a welding area defined on the first glass substrate and connecting to the first FPC through circuits, and a backlight unit opposite to the first glass substrate. The backlight unit has an outward second FPC for a purpose of power supply, wherein the front end of the second FPC is welded to the welding area on the first substrate. 
   In the second embodiment of the present invention, a second display module comprises a first glass substrate with a plurality of TFTs fabricated thereon, an second glass opposite to the first glass substrate and having a color filter adhered thereto, a liquid crystal layer sandwiched between the first and the second glass substrates, a driver IC mounted on the first glass substrate for driving the TFTs, and a first FPC, wherein back-end of the first FPC is connecting to the driver IC and the front-end thereof is extending outwardly from a side of the first glass substrate for being in contact with a system. The first FPC has a foldable part and the front end of the foldable part includes a welding area. The second display module also comprises a backlight unit opposite to the first glass substrate for providing lights to the display module, wherein the backlight unit has an outward second FPC for a purpose of power supply. The front end of the second FPC is welded to the welding area of the foldable part. The foldable part and second FPC are then bended to position the welding area at the rear side of the backlight unit. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The foregoing aspects and many of the attendant advantages of this invention will become more readily appreciated and understood by referencing the following detailed description in conjunction with the accompanying drawings, wherein: 
       FIG. 1  is a side view of an assembly of a display panel and a backlight unit in accordance with the prior art, showing a conventional connection of a TFT FPC and a LED FPC. 
       FIG. 2  is a side view of an LCD module in accordance with the prior art, showing the conventional connection of a TFT FPC and a LED FPC. 
       FIG. 3  is a side view of an LCD module in accordance with the first embodiment of the present invention, wherein a second FPC of a backlight unit is electrically connected to a first FPC of a display panel through circuits defined on the display panel. 
       FIGS. 4  is a top view of an LCD module in accordance with the first embodiment of the present invention. 
       FIG. 5  is a side view of an LCD module in accordance with the second embodiment of the present invention, wherein a first FPC of a display panel has a foldable part and a second FPC of a backlight unit is electrically connected to a welding area defined on the foldable part. 
       FIG. 6  is a sectional view of an LCD in accordance with the second embodiment of the present invention, wherein the foldable part is folded and fixed to the rear side of the backlight unit. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   Embodiment 1 
   Referring to  FIG. 3 , a first LCD module  3  of the first embodiment is shown. The LCD module  3  comprises a display panel  31  and a backlight unit  32  opposite to the display panel  31 , wherein the display panel  31  includes a first glass substrate  310  with a plurality of TFTs formed thereon and a second glass substrate  311  with a color filter adhered thereto. The color filter faces TFTs on the first glass substrate  310 . Between first glass substrate  310  and the second glass substrate  311  is sandwiched a LC layer for the image formation. Generally speaking, the dimension of the first glass substrate  310  is grater than that of the second glass substrate  311 . Thus, a portion of surface of the first glass substrate  310  is exposed after assembling the second glass substrate  311 , the first glass substrate  310  and the LC layer. The exposed surface of the first glass substrate  310  is provided for the mounting of driver ICs. As shown in the figure, a gate driver IC  312  is mounted on right side of the first glass substrate  310 , whereas a source driver IC  313  is mounted on front side of the first glass substrate  310 . 
   A first FPC  314  is constructed on a side of the first glass substrate  310  near the source driver IC  313 . Back-end of the first FPC  314  is electrically connected to the source driver IC  313  and the gate driver IC  312  through circuits defined on the first glass substrate  310 . The front-end of the first FPC  314  is in contact with a system to transmit signals produced therefrom to the display panel  31 . In the embodiment of the present invention, the first FPC  314  is TFT FPC. It is noted that welding areas  315  are formed on the first glass substrate  310  near a corner and are electrically connected to the first FPC  314  via circuits on the first glass substrate  310 . 
   In addition, a backlight unit  32  is opposite to the display panel  31  for providing illumination to the whole LCD module  3 . As shown in the figure, the backlight unit  32  includes a second FPC  321  fabricated for a purpose of providing power to a light source (e.g. LED) of the backlight unit  32 . The front-end of the second FPC  321  is connected to the welding area  315  on the first glass substrate  310  by soldering. Accordingly, the backlight unit  32  obtains power from the system through the second FPC  321  and the first FPC  314 . 
   Referring to  FIG. 4 , a top view of the display panel  31  is shown. The gate driver IC  312  and the source driver IC  313  are mounted on the right side and the front side of the first glass substrate  310 , respectively. The first FPC  314  fabricated on the side of the first glass substrate  310  is electrically connected to the source driver IC  313  via a circuit  316   a,  whereas the welding area  315  defined at a corner of the first glass substrate  310  is electrically connected to the source driver IC  313  via a circuit  316   b.    
   It is noted that since the front end of the second FPC  321  is welded on the display panel  31 , the welding area  315  provided for the connection of the second FPC  321  and the display panel  31  will not be injured even though the first FPC  314  is needed to be folded and bended in the following processes. In other words, drawbacks of peeling off and separation described in the prior art can be effectively avoided. In addition, though the position of the welding area  315  is defined at a corner of the first glass substrate  310 , this is not limited to the score and the spirit of the present invention. That is, the welding area  315  can be defined at any location on the first glass substrate  310 . 
   Embodiment 2 
   Referring to  FIG. 5 , a second LCD module  4  of the second embodiment is shown. As described above, the second LCD module  4  comprises a display panel  41  and a backlight unit  42  opposite to the display panel  41 , wherein the display panel  41  includes a first glass substrate  410 , a second glass substrate  311  and a LC layer sandwiched therebetween. A gate driver IC  412  and a source driver IC  413  are respectively mounted on the right side and the front side of the first glass substrate  410  for driving TFTs fabricated on the first glass substrate  410 . In addition, Back-end of a first FPC  414  is electrically connected to the source driver IC  413 , whereas the front-end thereof extends outwardly to connect a system. 
   It is noted that the first FPC  414  has a folding part  415  formed by substantially U-shaped cutting. A welding area  4150  is defined at the front end of the foldable part  415  for the connection of the second FPC  421  of the backlight unit  42 . As shown in the figure, the foldable part  415  can be folded and bended upward or downward according to the need of the processes. In this embodiment, the foldable part  415  is folded downward to attach to the backside of the backlight unit  42 . It is noted that the foldable part  415  can be formed by other kinds and shapes of cutting though the substantially U-shaped cutting is illustrated herein. 
   The backlight unit  42  opposite to the first glass substrate  410  is provided for illumination of the whole LCD module  4 . As described above, the backlight unit  42  includes a second FPC  421  for a purpose of providing power to a light source (e.g. LED) of the backlight unit  42 . In this embodiment, the front end of the second FPC  421  is connected to the welding area  4150  defined on the front end of the foldable part  415 . In a preferred embodiment, the front end of the second FPC  421  is connected to the welding area  4150  defined on the front end of the foldable part  415  by soldering. 
   After soldering the second FPC  421  of the backlight unit  42  to the welding area  4150  of the foldable part  415 , the foldable part  415  together with the second FPC  421  is turned around and attached to the backside of the backlight unit  42 . The welding area  4150  is fixed to the backlight unit  42  by adhesive material, such as glue, tape or the like. In other words, the second FPC  421  together with the foldable part  415  is folded to fix the welding area  4150  to the backside of the backlight unit  42 . As shown in  FIG. 6 , the foldable part  415  is folded and fixed to the backside of the backlight unit  42  casing. In addition, the foldable part  415  together with the second FPC  421  is turned around to fix the welding area  4150  of the foldable part  415  to the backside of the casing by a tape  5 . 
   In this embodiment, since the welding area  4150  is fixed to the backside of the casing of the LCD module  4 , the welding area  4150  will not be injured even though the first FPC  414  is needed to be folded and bended in the following processes. Accordingly, drawbacks of peeling off and chap in the prior art can be effectively avoided. It is noted that the position where the welding area  4150  fixed to is not used to limit the score and the spirit of the present invention. That is, the welding area  4150  can be fixed to any location of the LCD module  4 . For example, the welding area  4150  can be fixed on the display panel  41  or a position between the display panel  41  and the backlight unit  42 . 
   Because the welding area provided for the connection of the second FPC and first FPC is now defined on the display panel or attached to the casing of the backlight unit, the welding area will not be injured when the first FPC is needed to be folded and bended in the following processes. For the design illustrated in embodiment 1, the thickness of the first FPC is effectively decreased. In addition, the first FPC can be folded and bended much easier. 
   As to the design described in embodiment 2, since the foldable part is formed by cutting the first FPC and the welding area is defined on the foldable part, the foldable part can be folded and turned around to fix the welding area to the backlight unit after soldering the first FPC and second FPC together. Thus, problems existing in the prior arts can be solved too. 
   While the preferred embodiments of the present invention have been illustrated and described, it is appreciated that modifications and variations can be made therein without departing from the spirit and scope of the present invention. For example, disclosures in the present invention can be applied to various kinds of planar displays, such as plasma discharge panels (PDPs), field emission displays (FEDs) and organic light emitting diodes (OLEDs), etc.