Abstract:
The present invention provides a technique that is capable of preventing a separation of elements of the display panel of a slim display device in which the bending radius of a flexible printed circuit is small. A flexible printed circuit connects to a first side of the display panel and is bent in the vicinity of the first side, part of which is disposed between the back of a backlight and a holder. The holder has an opening or a depression in the vicinity of the first side of the backlight corresponding to the first side of the display panel. The flexible printed circuit has a portion which is deflected so that the top thereof projects into a space in the opening or the depression in the holder, as viewed in section perpendicular to the first side.

Description:
[0001]     The present application claims priority from Japanese application JP2004-135431 filed on Apr. 30, 2004, the content of which is hereby incorporated by reference into this application.  
       BACKGROUND OF THE INVENTION  
       [0002]     The present invention relates to a display device, and in particular, it relates to a technique that is effective in achieving a slim display device.  
         [0003]     Liquid-crystal display modules having a compact liquid-crystal display panel (for example, a TFT liquid-crystal display panel) are used as displays of cellular phones.  
         [0004]      FIG. 12  is an expanded schematic perspective view of a related-art liquid-crystal display module used as the display of a cellular phone and so on.  FIG. 13  is a sectional view of the module taken along line A-A′ of  FIG. 12 .  
         [0005]     As shown in  FIGS. 12 and 13 , the related-art liquid-crystal display modules used as displays of cellular phones etc. have a layered structure in which a liquid-crystal display panel (LCD) and a backlight (BL) are placed in this order in a die cast (LCA).  
         [0006]     Between the liquid-crystal display panel (LCD) and the backlight (BL), a double-coated spacer (SPA) is disposed, with which the liquid-crystal display panel (LCD) is fixed to the backlight (BL).  
         [0007]     On one side of the liquid-crystal display panel (LCD), a driver (DRV) having semiconductor chips for driving subpixels in the liquid-crystal display panel (LCD) is disposed. To the side of the liquid-crystal display panel (LCD), one end of a flexible printed circuit (FPC) is connected.  
         [0008]     The flexible printed circuit (FPC) is bent in the vicinity of the side of the liquid-crystal display panel (LCD), the other end of which is disposed between the backlight (BL) and the die cast (LCA).  
         [0009]     Circuit components (CIRs) are mounted to the part of the flexible printed circuit (FPC) which is disposed between the backlight (BL) and the die cast (LCA) and which corresponds to a hole  10  of the die cast (LCA)  
       SUMMARY OF THE INVENTION  
       [0010]     The liquid-crystal display modules, as shown in  FIGS. 12 and 13 , have recently been required to reduce the thickness.  
         [0011]     As described above, the flexible printed circuit (FPC) connects to one side of the liquid-crystal display panel (LCD) at one end, and is bent in the vicinity of the side of the liquid-crystal display panel (LCD), and is disposed between the backlight (BL) and the die cast (LCA) at the other end.  
         [0012]     Accordingly, for example, when the backlight (BL) is made slim to decrease the thickness of the liquid-crystal display module, the bending radius of the flexible printed circuit (FPC) becomes small as a necessary consequence.  
         [0013]     This increases the expanding stress (hereinafter, referred to as returning stress) of the flexible printed circuit (FPC), as shown by arrows A and A′ in  FIG. 14 .  
         [0014]     When the returning stress increases, the stripping stress to the double-coated spacer (SPA) that fixes the liquid-crystal display panel (LCD) to the backlight (BL), or the stripping stress to the end of the flexible printed circuit (FPC) is increased.  
         [0015]     When the stripping stress to the double-coated spacer (SPA) that fixes the liquid-crystal display panel (LCD) to the backlight (BL) becomes larger than the bonding strength of the double-coated spacer (SPA), the liquid-crystal display panel (LCD) may disadvantageously lift up from the backlight (BL).  
         [0016]     Also, when the stripping stress to the end of the flexible printed circuit (FPC) becomes larger than the bonding strength between the end of the flexible printed circuit (EPC) and the liquid-crystal display panel (LCD), the end of the flexible printed circuit (FPC) may lift up from the liquid-crystal display panel (LCD), so that the conductivity between the terminal of the flexible printed circuit (FPC) and the terminal of one substrate (glass substrate) of the liquid-crystal display panel (LCD) will be lost, thus affecting reliability.  
         [0017]     The present invention has been made to solve the above-described problems of the related-art techniques. Accordingly, an advantage of the invention is to provide a technique capable of preventing the lift-up of the display panel of a slim display device in which the bending radius of the flexible printed circuit is small.  
         [0018]     Another advantage of the invention is to provide a technique capable of preventing the lift-up of the flexible printed circuit of a slim display device in which the bending radius of the flexible printed circuit is small.  
         [0019]     The above and other advantages of the invention will be apparent from the following description of the preferred embodiments and the attached drawings.  
         [0020]     The invention will be briefly described below.  
         [0021]     To provide the above-described advantages, the invention comprises a display panel, a flexible printed circuit, and a holder that holds the display panel and the flexible printed circuit. The flexible printed circuit connects to a first side of the display panel and is bent in the vicinity of the first side, part of which is disposed between the display panel and the holder. The holder has an opening or a depression in the vicinity of the first side of the display panel. The flexible printed circuit deflects so that the part of the flexible printed circuit projects into the opening or the depression.  
         [0022]     The advantages of the invention will be briefly described below.  
         [0023]     (1) The invention provides a technique capable of preventing the lift-up of the display panel of a slim display device in which the bending radius of the flexible printed circuit is small.  
         [0024]     (2) The invention provides a technique capable of preventing the lift-up of the flexible printed circuit of a slim display device in which the bending radius of the flexible printed circuit is small. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0025]      FIG. 1  is a developed perspective view of the schematic structure of a liquid-crystal display module according to a first embodiment of the present invention;  
         [0026]      FIG. 2  is a sectional view of the liquid-crystal display module according to the first embodiment;  
         [0027]      FIG. 3  is a sectional view of a modification of the liquid-crystal display module according to the first embodiment;  
         [0028]      FIG. 4  is a sectional view of another modification of the liquid-crystal display module according to the first embodiment;  
         [0029]      FIG. 5  is a developed perspective view of the schematic structure of a liquid-crystal display module according to a second embodiment of the invention;  
         [0030]      FIG. 6  is a developed perspective view of the schematic structure of a modification of the liquid-crystal display module according to the second embodiment;  
         [0031]      FIG. 7  is a sectional view of a liquid-crystal display module according to a third embodiment of the invention;  
         [0032]      FIG. 8  is a sectional view of a modification of the liquid-crystal display module according to the third embodiment;  
         [0033]      FIG. 9  is a sectional view of another modification of the liquid-crystal display module according to the third embodiment;  
         [0034]      FIG. 10  is a sectional view of still another modification of the liquid-crystal display module according to the third embodiment;  
         [0035]      FIG. 11  is a sectional view of yet another modification of the liquid-crystal display module according to the third embodiment;  
         [0036]      FIG. 12  is an expanded schematic perspective view of the schematic structure of a related-art liquid-crystal display module used as the display of a cellular phone and so on.  
         [0037]      FIG. 13  is a sectional view of the module taken along line A-A′ of  FIG. 12 ; and  
         [0038]      FIG. 14  is a diagram for describing the problems of the related-art liquid-crystal display module.  
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0039]     The present invention is described in detail below based on embodiments, with reference to the attached drawings.  
         [0040]     Components that have the same function are given the same reference numerals and their description will be omitted in the drawings.  
       First Embodiment  
       [0041]      FIG. 1  is a developed perspective view of the schematic structure of a liquid-crystal display module according to a first embodiment of the present invention; and  FIG. 2  is a sectional view of the liquid-crystal display module according to the first embodiment, showing the same part as that of  FIG. 13 .  
         [0042]     The liquid-crystal display panel (LCD) is constructed such that a glass substrate (TFT) including a thin-film transistor, a drain line, a gate line, etc. and a glass substrate (CF) including a counter electrode, a color filter, etc. are bonded together via a sealing agent, between which liquid crystal is sealed. Since the structures of the glass substrate (TFT) and the glass substrate (CF) have no relation to the invention, the description thereof is omitted here.  
         [0043]     This embodiment is different from the related-art liquid-crystal display module shown in  FIGS. 12 and 13  in that the die cast (LCA) (also referred to as a holder) has a hole (opening)  11 .  
         [0044]     In this embodiment, the flexible printed circuit (FPC) is inserted in the hole  11  formed in the die cast (LCA) and deflects so that the top projects into space in the hole  11 .  
         [0045]     Thus, in this embodiment, the above-described returning stress can be absorbed even when the liquid-crystal display module is made slim, so that the bending radius of the flexible printed circuit (FPC) is small.  
         [0046]     Accordingly, the liquid-crystal display panel (LCD) is prevented from lifting up from the backlight (BL), or the end of the flexible printed circuit (FPC) is prevented from lifting up from the liquid-crystal display panel (LCD).  
         [0047]     It is apparent from the foregoing description that the embodiment may have a hole or depression in place of the hole  11  formed in the die cast (LCA).  
         [0048]     In a modification of the embodiment of the invention, the hole  11  is located such that the hole  11  does not overlap with the side  12  of the backlight (BL) corresponding to the terminal side of the glass substrate (TFT) of the liquid-crystal display panel (LCD), in plan view (as viewed from arrow B of  FIG. 2 ).  
         [0049]     In this case, as shown in  FIG. 4 , it is preferable that the distance (T 2  in  FIG. 4 ) between the end of the hole  11  adjacent to the side  12  of the backlight (BL) and the side  12  of the backlight (BL) be within 2 mm.  
         [0050]     In another modification of the embodiment, the hole  11  is located such that the hole  11  overlaps with the side  12  of the backlight (BL) in plan view.  
         [0051]     In this case, as shown in  FIG. 3 , it is preferable that the distance (T 1  in  FIG. 3 ) between the end of the hole  11  outside the backlight (BL) and the side  12  of the backlight (BL) be within 4 mm.  
         [0052]     In this embodiment, between the glass substrate (TFT) of the liquid-crystal display panel (LCD) and the backlight (BL), a double-coated spacer (SPA) is disposed, with which the liquid-crystal display panel (LCD) is fixed to the backlight (BL), in plan view.  
         [0053]     Alternatively, another fixing means may be used in place of the double-coated spacer (SPA). In this case, a nonadhesive spacer may be disposed, or alternatively, the spacer may be omitted. Ditto for the following embodiments.  
       Second Embodiment  
       [0054]      FIG. 5  is a developed perspective view of the schematic structure of a liquid-crystal display module according to a second embodiment of the invention.  
         [0055]     Although the liquid-crystal display module of this embodiment is different from the liquid crystal display module according to the first embodiment in that the die cast (LCA) has claws (CLs), with which the liquid-crystal display panel (LCD) is fixed, the other structures are the same as those thereof, so that their repeated description will be omitted here.  
         [0056]      FIG. 6  is a developed perspective view of the schematic structure of a modification of the liquid-crystal display module according to the second embodiment.  
         [0057]     The backlight (BL) generally includes an optical waveguide, optical sheets (e.g., an upper diffusion sheet, two lens sheets, and a lower diffusion sheet), and a mold that accommodates the optical waveguide and the optical sheets.  
         [0058]     The liquid-crystal display module shown in  FIG. 6  has the claws (CL) that fix the liquid-crystal display panel (LCD) on the mold of the backlight (BL).  
         [0059]     According to this embodiment, the vertical movement of the liquid-crystal display panel (LCD) can be limited.  
       Third Embodiment  
       [0060]      FIG. 7  is a sectional view of a liquid-crystal display module according to a third embodiment of the invention, showing the section of the same part as in  FIG. 13 .  
         [0061]     The liquid-crystal display module of this embodiment has a reflection liquid-crystal display panel (RLCD) in place of the liquid-crystal display panel (LCD) according to the foregoing embodiments. Accordingly, in this embodiment, the backlight (BL) is omitted, and the flexible printed circuit (FPC) is fixed to the reflection liquid-crystal display panel (RLCD) with the double-coated spacer (SPA).  
         [0062]     The other structures are the same as those of the first embodiment, their repeated description will be omitted here.  
         [0063]     Also in this embodiment, the flexible printed circuit (FPC) is inserted into the hole (or depression)  11  of the die cast (LCA) and deflects so that the top projects into the space of the hole  11 .  
         [0064]     Thus, also in this embodiment, the above-described returning stress can be absorbed even when the liquid-crystal display module is made slim, so that the bending radius of the flexible printed circuit (FPC) is small.  
         [0065]     Accordingly, the reflection liquid-crystal display panel (RLCD) is prevented from lifting up from the backlight (BL), or the end of the flexible printed circuit (FPC) is prevented from lifting up from the reflection liquid-crystal display panel (RLCD).  
         [0066]     In a modification of the embodiment, the hole  11  is located such that the hole  11  does not overlap with the terminal side of the glass substrate (TFT) of the reflection liquid-crystal display panel (RLCD), in plan view (as viewed from arrow B of  FIG. 7 ).  
         [0067]     In this case, as shown in  FIG. 9 , it is preferable that the distance (T 2  in  FIG. 9 ) between the end of the hole  11  adjacent to the reflection liquid-crystal display panel (RLCD) and the terminal side of the reflection liquid-crystal display panel (RLCD) be within 2 mm.  
         [0068]     In another modification of the embodiment, the hole  11  is located such that the hole  11  overlaps with the terminal side of the glass substrate (TFT) of the reflection liquid-crystal display panel (RLCD), in plan view.  
         [0069]     In this case, as shown in  FIG. 8 , it is preferable that the distance (T 1  in  FIG. 8 ) between the end of the hole  11  outside the reflection liquid-crystal display panel (RLCD) and the terminal side of the glass substrate (TFT) of the reflection liquid-crystal display panel (RLCD) be within 4 mm.  
         [0070]     In this embodiment, the die cast (LCA) may have claws to fix the reflection liquid-crystal display panel (RLCD), as shown in  FIG. 5 .  
         [0071]     In this embodiment, an organic electroluminescent (EL) display panel may be used in place of the reflection liquid-crystal display panel (RLCD).  
         [0072]      FIG. 10  is a sectional view of still another modification of the liquid-crystal display module according to the third embodiment.  
         [0073]     The liquid-crystal display module shown in  FIG. 10  is different from the liquid-crystal display module shown in  FIG. 7  in that a printed circuit board (PCB) having circuit components (CIRs) is disposed between the reflection liquid-crystal display panel (RLCD) and the die cast (LCA) and that the printed circuit board (PCB) is fixed to the reflection liquid-crystal display panel (RLCD) with the double-coated spacer (SPA). However, the other structures are the same as those of the liquid-crystal display module of  FIG. 7 . Accordingly, their repeated description will be omitted here.  
         [0074]     The flexible printed circuit (FPC) has no circuit component (CIR) and is used to electrically connect the printed circuit board (PCB) and the reflection liquid-crystal display panel (RLCD).  
         [0075]      FIG. 11  is a sectional view of yet another modification of the liquid-crystal display module according to the third embodiment.  
         [0076]     The liquid-crystal display module shown in  FIG. 11  is different from the liquid-crystal display module shown in  FIG. 7  in that a front light (FL) is disposed in front of the reflection liquid-crystal display panel (RLCD) (on the observer side). However, the other structures are the same as those of the liquid-crystal display module of  FIG. 7 . Accordingly, their repeated description will be omitted here.  
         [0077]     While the invention made by the inventor has been specifically described based on the embodiments, it is to be understood that the invention is not limited to the foregoing embodiments and various modifications may be made without departing from the spirit or scope of the invention.