Abstract:
To provide a liquid crystal display module that eliminates the loss of light emitted from a light source. The present invention provides a liquid crystal display module including: a liquid crystal display panel; and a backlight, wherein the liquid crystal display panel includes an upper polarization plate and a lower polarization plate, the backlight is configured by a light source and a light guide plate, the light guide plate is configured in such a manner that the thickness of an incident face where light of the light source enters is larger than that of a portion opposed to the lower polarization plate, a light shielding member and a reflection member arranged on the light shielding member are provided at portions, of the liquid crystal display panel, corresponding in the upper direction to the incident face of the light guide plate, and the reflection member is formed along the light guide plate.

Description:
CLAIM OF PRIORITY 
       [0001]    The present application claims priority from Japanese Application JP 2007-007601 filed on Jan. 17, 2007, the content of which is hereby incorporated by reference into this application. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a liquid crystal display module in which a backlight is mounted, and particularly to a technique suitable for use in a small liquid crystal display module used for a mobile phone and the like. 
         [0004]    2. Description of the Related Art 
         [0005]      FIG. 9  is a diagram showing a cross sectional configuration of main components of a conventional liquid crystal display module. 
         [0006]    A liquid crystal display panel is configured in such a manner that a liquid crystal layer (not shown) is sandwiched between a TFT substrate  11  and a color filter substrate  12  (hereinafter, referred to as CF substrate  12 ). The TFT substrate  11  is larger than the CF substrate  12  in size, and a driver chip  13  for controlling the driving of the liquid crystal display panel is arranged at a region, on the TFT substrate  11 , that is not overlapped with the CF substrate  12 . Further, an upper polarization plate  14  is arranged on the CF substrate  12 , and a lower polarization plate  20  is arranged under the TFT substrate  11 . Furthermore, a backlight is arranged under the liquid crystal display panel so as to configure a liquid crystal display module. 
         [0007]    The backlight is configured by a light source  18  such as an LED arranged on a flexible print substrate  15  (hereinafter, referred to as FPC  15 ), and a light guide plate  17  through which light emitted from the light source  18  is guided to the entire liquid crystal display panel. Optical sheets  22  are arranged between the light guide plate  17  and the liquid crystal display panel. The optical sheets include, for example, an upper diffusion sheet, an upper prism sheet, a lower prism sheet, a lower diffusion sheet, and the like. A reflection sheet  23  is arranged under the light guide plate  17  so as to function to direct light guided under the light guide plate  17  toward the liquid crystal display panel. In order to satisfy the requirements of a thinner liquid crystal display apparatus, the light guide plate  17  is configured to be thinner except for an incident face opposed to the light source  18 . Because the size of an LED that is suitable at present as the light source  18  is large, the thickness of the incident face is configured to be large. The incident face of the light guide plate  17  is configured to be large in size in accordance with the size of the LED. In  FIG. 9 , the reference numeral  16  denotes a mold frame, and the liquid crystal display module is configured in such a manner that the liquid crystal display panel is arranged above the frame-like mold frame and the backlight is arranged thereunder. 
         [0008]    As shown in  FIG. 9 , a light shielding tape  31  is arranged on the TFT substrate  11  on the side where the lower polarization plate  20  is arranged and at a position above the light source  18 . Further, a spacer tape  91  which has an L-shaped cross section as shown in  FIG. 10  and which is configured by, for example, a white PET is arranged on the light shielding tape  31  so that unnecessary light is prevented from entering the liquid crystal display panel. 
         [0009]    JP-A No. 1995-294921 is one of well-known techniques which describes a liquid crystal display module in which an incident face of the light guide plate is thus configured to be large. 
         [0010]    In the case of the configuration shown in  FIG. 9 , a space  90  is formed between the light guide plate  17  and the spacer tape  91 , and thus it has been found that a problem arises in that the space  90  causes the loss of light. 
         [0011]    In view of the above-described problem, an object of the present invention is to provide a liquid crystal display module that eliminates the loss of light emitted from a light source. 
       SUMMARY OF THE INVENTION 
       [0012]    According to one aspect of the present invention, there is provided a liquid crystal display module including: a liquid crystal display panel; and a backlight, wherein the liquid crystal display panel includes an upper polarization plate and a lower polarization plate, the backlight is configured by a light source and a light guide plate, the light guide plate is configured in such a manner that the thickness of a portion where light emitted from the light source enters (in other words, the thickness of an incident face) is larger than that of a portion opposed to the lower polarization plate (in other words, the height of the light guide plate corresponding to a display area of the liquid crystal display panel), a light shielding member such as a light shielding tape and a reflection member arranged on the light shielding member are provided at portions, of the liquid crystal display panel, opposed in the upper direction to the incident face of the light guide plate, and the reflection member is formed along the light guide plate. The light guide plate is formed in a planar shape in which the thickness of a portion corresponding to a display area is equal, or formed in a wedge shape in which the thickness of a portion corresponding to a display area is gradually changed in accordance with a distance from a light source. The light guide plate formed in any one of the above-described shapes can be applied in the present invention. For example, if the light guide plate formed in a wedge shape is used, the thickness of a portion opposed to the lower polarization plate of the present invention (in other words, the height of the light guide plate opposed to a display area of the liquid crystal display panel) may mean the thickness of the light guide plate or the height of the light guide plate corresponding to a display area nearer the light source. In yet other words, the present invention can be applied to a liquid crystal display module having a light guide plate configured in such a manner that the thickness of an incident face of the light guide plate is larger than that of a face opposite to the incident face. 
         [0013]    By employing such a configuration, it is possible to provide a liquid crystal display module that eliminates the loss of light emitted from a light source. 
         [0014]    In the liquid crystal display module, the light shielding member is arranged from an end portion of the liquid crystal display panel (in this case, if the light shielding member is formed from an end portion of the liquid crystal display panel, the highest light shielding effect is exhibited. If the light shielding member is formed at least up to a position above the light source, the light shielding effect is exhibited.) up to a position that is not overlapped with a portion of the arrangement position of the lower polarization plate, and the reflection member is arranged at a position, on the light shielding member, that is not overlapped with a position above the arrangement position of the light source. Accordingly, the configuration can be applied to a thinner liquid crystal display module. 
         [0015]    As one of concrete examples of the reflection member, it is conceivable that the reflection member is configured by a base portion and a sheet portion. As one example in this case, the base portion and the sheet portion can be integrally configured. As described above, if the reflection member is integrally formed by the base portion and the sheet portion, the number of components can be reduced, resulting in excellence in workability when assembling the product. Further, the reflection sheet is usually arranged under the light guide plate. One of the characteristics of the present invention is that the reflection member of the present invention and the reflection sheet arranged under the light guide plate are configured by using the same material. 
         [0016]    Further, as another configuration example, it is conceivable that the reflection member is configured by the base portion and the sheet portion that are different from each other. Also in this case, the reflection sheet is arranged under the light guide plate. It is conceivable that the reflection member of the present invention and the reflection sheet arranged under the light guide plate are configured by using the same material. 
         [0017]    As described above, in the case where the reflection member is configured by the base portion and the sheet portion that are different from each other, one of the characteristics of the present invention is that the base portion is configured by a PET in a rectangular parallelepiped shape and the reflection member is configured by a sheet-like member. In this case, if one end of the reflection member is attached to the base portion, and the other end thereof is attached to the light shielding member, it is conceivable that the formation of complex shapes is not necessary, and a liquid crystal display module that can eliminate the limitation of processing the components. 
         [0018]    According to another aspect of the present invention, there is provided a liquid crystal display module including: a liquid crystal display panel; and a backlight, wherein the backlight is a backlight of a side-light type in which a light source is arranged on a side face of a light guide plate, the light guide plate is configured in such a manner that the thickness of an incident face where light of the light source enters is larger than that of a face positioned opposite to the incident face, a light shielding member is formed at a portion, of the liquid crystal display panel, opposed in the upper direction to the incident face of the light guide plate, a sheet-like reflection member along the shape of the light guide plate is formed on the light shielding member, and the sheet-like reflection member is configured in such a manner that one end thereof is attached to a base portion arranged on the light shielding member and the other end thereof is attached to the light shielding member. 
         [0019]    Even in such a configuration, it is possible to provide a liquid crystal display module that eliminates the loss of light emitted from a light source. 
         [0020]    Further, if the light shielding member is, at least, arranged from a position above the light source up to a position that is not overlapped with a portion of the arrangement position of the lower polarization plate, and the reflection member is arranged at a position, on the light shielding member, that is not overlapped with a position above the arrangement position of the light source, it is possible to satisfy the requirements for making thinner the whole liquid crystal display module. 
         [0021]    Further, the reflection sheet is usually arranged under the light guide plate. The reflection member of the present invention and the reflection sheet can be configured by using the same material. Furthermore, the above-described base portion may be configured by, for example, a PET in a rectangular parallelepiped shape. In a precise sense, the base portion is not necessarily formed in a rectangular parallelepiped shape, but a substantially rectangular parallelepiped shape is included in the rectangular parallelepiped shape of the present invention. 
         [0022]    Further, if a distance between the light guide plate and the reflection member arranged in the normal-line direction of the light guide plate is as large as 0.02 mm or less, the effects of the present invention can be obtained. 
         [0023]    The light guide plate of the present invention has a cross section inclined from a portion (incident face) where light of the light source enters, at least to a position of a portion opposed to the lower polarization plate. 
         [0024]    According to still another aspect of the present invention, there is provided a liquid crystal display module including: a liquid crystal display panel; and a backlight, wherein the liquid crystal display panel includes an upper polarization plate and a lower polarization plate, the backlight is configured by a light source and a light guide plate, the light guide plate is configured in such a manner that a portion where light of the light source enters is larger than that opposed to the lower polarization plate in size, and a light shielding member such as a light shielding tape and a reflection member arranged on the light shielding member are provided at portions, of the liquid crystal display panel, corresponding in the upper direction to the incident face of the light guide plate. 
         [0025]    In this configuration, the light shielding member is, at least, arranged from a position above the light source up to a position that is not overlapped with a portion of the arrangement position of the lower polarization plate, and the reflection member is arranged at a position, on the light shielding member, that is not overlapped with a position above the arrangement position of the light source. This configuration is preferable in terms of achievement of making thinner the whole liquid crystal display module. 
         [0026]    According to the present invention, it is possible to provide a liquid crystal display apparatus that eliminates the loss of light emitted from a light source. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]      FIG. 1  is a diagram showing the whole configuration of a liquid crystal display module according to the present invention; 
           [0028]      FIG. 2  is a diagram showing a cross sectional configuration taken along the line A-A′ in the liquid crystal display module of the present invention in  FIG. 1 ; 
           [0029]      FIG. 3  is a diagram showing a cross sectional configuration of main components taken along the line A-A″ in the liquid crystal display module in  FIG. 1 ; 
           [0030]      FIG. 4  is a diagram showing a configuration of a second embodiment obtained by further improving the configuration of a first embodiment; 
           [0031]      FIG. 5  is a diagram showing one concrete example of a reflection sheet of the second embodiment; 
           [0032]      FIG. 6  further shows a configuration of main components of the configuration of the second embodiment; 
           [0033]      FIG. 7  is a diagram showing a third embodiment and shows still another configuration example of the second embodiment; 
           [0034]      FIG. 8  is a diagram showing a state of a base portion  71  and a sheet portion  72  in the third embodiment; 
           [0035]      FIG. 9  is a diagram showing a cross sectional configuration of main components of a conventional liquid crystal display module; and 
           [0036]      FIG. 10  is a diagram showing a configuration of a spacer tape used in a convention liquid crystal display module. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0037]    Hereinafter, the present invention will be described in detail by using the drawings. 
       First Embodiment 
       [0038]      FIG. 1  shows a configuration of a liquid crystal display module  10  according to the present invention. 
         [0039]    A liquid crystal display panel is configured in such a manner that a TFT substrate  11  configured by an insulating transparent substrate such as a glass substrate and a plastic substrate is overlapped with a color filter substrate  12  (hereinafter, referred to as CF substrate  12 ) so as to sandwich a liquid crystal layer. In addition, a driver chip  13  for controlling the driving of the liquid crystal display panel is formed at a region, on the TFT substrate  11 , that is not overlapped with the CF substrate  12 . Further, in order to supply a signal to the driver chip  13 , one end of a flexible print substrate  15  is arranged. Furthermore, an upper polarization plate  14  is arranged on the CF substrate  12 , and a lower polarization plate is arranged on the TFT substrate  11 . Since the driver chip  13  is arranged on the TFT substrate  11 , the CF substrate is smaller than the TFT substrate in size. It is obvious that when the driver chip is arranged on the CF substrate, the CF substrate is larger than the TFT substrate in size. 
         [0040]    The liquid crystal display panel is arranged above a frame-like mold frame  16 . Under the mold frame  16 , there are arranged optical sheets (not shown) such as an upper diffusion sheet, an upper prism sheet, a lower prism sheet, and a lower diffusion sheet, a light guide plate  17 , and a reflection sheet  19 , so that they are sandwiched by a part of the other end of the flexible print substrate  15  and the mold frame  16 . On the other end of the flexible print substrate  15 , there are arranged light sources  18  such as LEDs while being opposed to a side face of the light guide plate  17 . 
         [0041]    One side face (incident face) of the light guide plate  17  is arranged so as to be opposed to the light sources  18 , and the light guide plate  17  is accommodated in the mold frame  16  on the side opposite to the side where the liquid crystal display panel is accommodated. In addition, a reflection sheet  23  arranged under the light guide plate  17  is attached to the mold frame  16  according to a positional relation as shown in  FIG. 2  by an adhesive formed at the circumference of the reflection sheet  23 . A backlight in which the light sources are thus arranged on a side face of the light guide plate is generally called a backlight on a side-light side. 
         [0042]      FIG. 2  is a diagram showing a cross sectional configuration taken along the line A-A′ in the liquid crystal display module of the present invention in  FIG. 1 .  FIG. 2  shows a state in which the liquid crystal display module shown in  FIG. 1  is accommodated in an upper frame  21  and a lower frame  22 . 
         [0043]    As shown in  FIG. 2 , a lower polarization plate  20  is arranged even on the TFT substrate  11 , and optical sheets  22  are arranged between the light guide plate  17  and the liquid crystal display panel. The reflection sheet  23  is arranged under the light guide plate  17 . 
         [0044]      FIG. 3  is a diagram showing a cross sectional configuration of main components taken along the line A-A′ in the liquid crystal display module in  FIG. 1 . In  FIG. 3 , a light shielding member  31  extends from a position above the light sources  18  toward the direction of the lower polarization plate  20 . The light shielding member  31  is preferably arranged to the extent not to overlap with the lower polarization plate  20 . 
         [0045]    In the embodiment, a reflection member  32  in a planar shape is arranged in place of a spacer tape with an L-shaped cross section that is configured by a white PET and arranged on the light shielding member  31  such as a light shielding tape. 
         [0046]    As described above, the reflection member  32  is arranged on the light shielding member  31  to the extent not to reach a position above the light sources  18 . Accordingly, light emitted from the light guide plate  17  before reaching the optical sheets  22  can be returned to the light guide plate  17  side by the reflection member  32 , and light from the light sources  18  can be guided to the liquid crystal display panel without loss. As a material of the reflection member  32  in the embodiment, for example, the same material as the reflection sheet  23  arranged under the light guide plate  17  may be used. It is conceivable that the reflection member  32  is configured by, for example, a silver sheet formed by coating the surface of a PET as a base material with silver. 
         [0047]    In the embodiment, the reflection member  32  is not arranged above the light sources  18  due to a problem that the whole thickness of the liquid crystal display module becomes larger if the thickness of the reflection member  32  is larger than the distance of a space between the light sources  18  and the light shielding member  31 . Therefore, in the case where the whole thickness of the liquid crystal display module is not considered at all, it is possible to arrange the reflection member  32  to the extent to reach a position above the light sources  18 . 
       Second Embodiment 
       [0048]    In the case of the configuration of the first embodiment, there occurs a problem that light L leaks toward the liquid crystal display panel from between the reflection member  32  and the optical sheets  22  due to the planar shape of the reflection member  32  as shown in  FIG. 3 , the light enters from a side face of the polarization plate  20 , or directly enters the TFT substrate  11  without passing through the polarization plate  20 . The light is one that is not controlled by the polarization plate, or unpolarized light that has not passed through the polarization plate. Thus, the light is not preferable as light that enters the liquid crystal display panel. Accordingly, it is desirable to eliminate such the light L as much as possible. In addition, a space between the light guide plate  17  and the reflection member  32  as shown in  FIG. 3  is likely to cause the TFT substrate  12  to bend when a force is applied from a region, on the TFT substrate  11 , that is not overlapped with the CF substrate  12 , or from a position above the CF substrate  12 . Accordingly, it is desirable to minimize the space as small as possible. Further, in the case where the incident face of the light guide plate is shaped to be wide as described in the present invention, it is necessary to devise in order to economically and effectively collect light. 
         [0049]      FIG. 4  is a diagram showing a configuration of a second embodiment obtained by further improving the configuration of the first embodiment. 
         [0050]    The second embodiment shown in  FIG. 4  shows a state in which a reflection member  41  is formed along the shape of the light guide plate  17 . In  FIG. 4 , the light shielding member  31  extends from a position above the light sources  18  toward the direction of the lower polarization plate  20 . The light shielding member  31  is preferably arranged to the extent not to overlap with the lower polarization plate  20 . 
         [0051]    The shape of the reflection member  41  will be described in detail by using  FIG. 5 . 
         [0052]    The reflection member  41  in the second embodiment can be configured by using, for example, the same material as the reflection sheet  23  arranged under the light guide plate  17 . The reflection member  41  in the second embodiment is configured by a base portion  411  and a sheet portion  412 . For example, a width w 1 , a length w 2 , and a height t 1  of the base portion are as large as 0.85 mm, 34.7 mm, and 0.21 mm, respectively, and a thickness t 2  of the sheet portion  412  is as large as 0.06 mm. In the second embodiment, it is important to arrange the reflection member  41  along the shape of the light guide plate  17 . Due to a problem of processing accuracy of the reflection member  41 , there is shown an example, as a concrete configuration of the reflection member  41  along the shape of the light guide plate  17 , that the base portion  411  and the sheet portion  412  are separately configured. Even if the sheet portion  412  is brought in contact with the light guide plate  17 , stress is not transmitted to the liquid crystal display panel and the light guide plate  17  by flexibility of the sheet portion  412 . In the second embodiment, in addition to the base portion  411 , an end portion of the sheet portion  412  is arranged so as to be attached to the light shielding member  31  configured by, for example, a light shielding tape. 
         [0053]      FIG. 6  further shows a configuration of main components of the configuration of the second embodiment. 
         [0054]    As shown in  FIG. 6 , one of the characteristics of the second embodiment is that the reflection member  41  arranged nearer the liquid crystal display panel is arranged along the shape of the light guide plate  17 . The arrangement along the shape of the light guide plate in the second embodiment means a state in which the reflection sheet  41  ( 412  in the case of  FIG. 6 ) is arranged apart from the light guide plate  17  in the vertical direction by 0.02 mm at the most, in other words, the reflection sheet  41  is arranged within a range of 0.02 mm or less from the light guide plate  17  in the vertical direction. In a normal situation, the reflection member  41  is ideally arranged so as to be closely attached along the shape of the light guide plate  17 . However, when the mass productivity of the product and processing accuracy are taken into account, the configuration such as the second embodiment is a real solution. In view of this point, the second embodiment is thus configured. 
         [0055]    Further, it is important that the reflection member  41  ( 412  in the case of  FIG. 6 ) is not arranged up to a position B 2  where the reflection member  41  is to be overlapped with a position above the light sources  18 . This is because the whole thickness of the liquid crystal display module becomes larger when the thickness of the reflection member  41  ( 412  in the case of  FIG. 6 ) is larger that a space between the light sources  18  and the light shielding member  31 . It is obvious that if the whole thickness of the liquid crystal display module is not considered at all, such a limitation is not necessary. When the mass productivity is taken into account, it is conceivable that the reflection member  41  ( 412  in the case of  FIG. 6 ) is preferably arranged so as not to cross an end portion B 1  of the incident face of the light guide plate  17 . 
       Third Embodiment 
       [0056]      FIG. 7  is a diagram showing a third embodiment and shows still another configuration example of the second embodiment. 
         [0057]    In  FIG. 7 , the light shielding member  31  extends from a position above the light sources  18  toward the direction of the lower polarization plate  20 . The light shielding member  31  is preferably arranged to the extent not to overlap with the lower polarization plate  20 . 
         [0058]    In the second embodiment, as a concrete configuration example for arranging the reflection member  41  arranged nearer the liquid crystal display panel along the shape of the light guide plate  17 , there is shown an example in which the reflection member  41  is integrally configured by the base portion  411  and the sheet portion  412 . However, a base portion  71  and a sheet portion  72  of the reflection member  41  are separately configured in the third embodiment. In the case of such a configuration, to be exact, the base portion  71  does not need to carry out a reflection function, and accordingly, the base portion  71  may not be a reflection member, but is regarded as a part of a reflection member in the embodiment. In the case of the configuration of the third embodiment, the base portion  71  configured by, for example, a white PET or the like is arranged nearer the liquid crystal display panel, and the sheet portion  72  is arranged so as to be attached to the base portion  71 , as shown in  FIG. 7 . In the case of the third embodiment, the sheet portion  72  is attached to the base portion  71 , and at the same time, an end portion thereof is arranged so as to be attached to the light shielding member  31 . As a material of the sheet portion  71 , it is conceivable that the sheet portion  71  is configured by, for example, a silver sheet formed by coating the surface of a PET as a base material with silver. It is conceivable that the sheet portion is configured by using the same material as the reflection sheet arranged under the light guide plate. A thickness t 3  of the sheet portion  71  is as large as about 0.06 mm (no less than 0.04 mm and no more than 0.08 mm) as similar to the thickness of the sheet portion shown in the second embodiment. 
         [0059]      FIG. 8  is a diagram showing a state of the base portion  71  and the sheet portion  72  in the third embodiment. Unlike the concrete example shown in the second embodiment, the sheet portion  72  is different from the base portion  71  as constituent elements. The matters described by using  FIG. 6  in the second embodiment are the same in the third embodiment.