Abstract:
Provided is a liquid crystal display device, including a liquid crystal display panel, a liquid crystal display protection panel protecting a display surface of the liquid crystal display panel, and a frame supporting the liquid crystal display protection panel on a periphery of a surface of the liquid crystal display protection panel, wherein a gap is installed between a edge surrounding the liquid crystal display protection panel and the frame.

Description:
TECHNICAL FIELD 
       [0001]    It relates to a liquid crystal display device. In particular, it relates to a liquid crystal display device such as a portable information terminal, which is equipped with a liquid crystal display device including a liquid crystal display (LCD) protection panel and a liquid crystal module including a liquid crystal display (LCD) panel. 
         [0002]    Liquid crystal display devices have been widely used for display units of various electronic devices such as a portable information terminal such as a cell phone or a PDA (personal digital assistants), a portable PC (personal computer) such as a laptop PC, a desktop PC, and a television on account of being thin and lightweight as well as because of low-voltage driving and power-saving. 
         [0003]      FIG. 1  is a front view of a conventional cell phone equipped with a liquid crystal display device. 
         [0004]    A cell phone  10  of  FIG. 1  includes a stationary-side case  1  and a movable-side case  3  coupled with the stationary-side case  1  through a hinge  2  in a foldable manner. In the illustrated example of  FIG. 1 , the movable-side case  3  of the cell phone  10  is opened. 
         [0005]    The stationary-side case  1  has a flat, substantially rectangular shape. An inner surface  4  of the stationary-side case  1  is provided with, for example, plural push buttons  5 ,  6 , and  7 . Further, an inner surface  8  of the movable-side case  3  is provided with, for example, a liquid crystal display device  9 . 
         [0006]      FIG. 2  is a cross-sectional view of the liquid crystal display device  9  of  FIG. 1 . 
         [0007]    As shown in  FIG. 2 , the liquid crystal display device  9  includes a front case  11 , a rear case  12 , and an LCD (liquid crystal display) protection panel  13 . 
         [0008]    The front case  11  is a molded case made of a resin or magnesium alloy, for example. A lower surface of the front case  11  is bonded to an upper end of the rear case  12  by means of claws or screws. 
         [0009]    A liquid crystal display protection panel mounting surface  11   a  extends from an upper portion of the front case  11 . The LCD protection panel  13  made of polymethyl methacrylate (PMMA) as an acrylic polymer is placed on the liquid crystal display protection panel mounting surface  11   a  through a double-faced adhesive tape  14 , for example. 
         [0010]      FIG. 3  is an enlarged view of a portion A enclosed by the dotted line of  FIG. 2 . As shown in  FIG. 3 , the liquid crystal display protection panel mounting surface  11   a  is a flat surface substantially parallel to the horizontal. An outer edge of the LCD protection panel  13  is fixed onto the liquid crystal display protection panel mounting surface  11   a  by means of the double-faced adhesive tape  14 . Further, there is no space but a small gap resulting from dimensional tolerances, between an end face of the LCD protection panel  13  and an inner surface of the upper portion of the front case  11 . 
         [0011]    Referring back to  FIG. 2 , a concave liquid crystal module holder  16  having a substrate  15  attached to the bottom is provided inside the front case  11 . Electronic components such as a chip capacitor are mounted onto the substrate  15  but are not illustrated in  FIG. 2 . Liquid crystal modules  17  and  18  are nested into the concave portion of the liquid crystal module holder  16 . By the way, the liquid crystal module  18  is a liquid crystal display (LCD) panel, and the liquid crystal module  17  is a LCD panel holder for holding the LCD panel  18 . 
         [0012]    An upper edge of the liquid crystal module holder  16  is in contact with a lower side of the upper portion of the front case  11 . The liquid crystal module holder  16  supports the front case  11 . Further, a dustproof gasket  19  made of cushioning such as urethane form rubber is put on an upper edge of the LCD panel  18 . The dustproof gasket  19  is in contact with a lower surface of the LCD protection panel  13 . This structure protects the liquid crystal modules  17  and  18  from powder dust. 
         [0013]    In addition, Japanese Laid-open Patent Publication No. 2004-111153 proposes a backlight and a liquid crystal display device, which include a light source supporting member for supporting a light source to a chassis or a corner portion of a light reflecting member, and in which a reflector is partially positioned between the chassis and the light source supporting member, and the light source supporting member controls movement of a front edge portion of the reflector relative to the chassis in a direction parallel to a front side of a light guide. 
         [0014]    However, the structure of  FIG. 2  involves the following problems. Referring to cross-sectional views of  FIGS. 4A and 4B  similar to  FIG. 2 , the problems are described below. 
         [0015]    The LCD protection panel  13  tends to expand in the direction of the arrow of  FIG. 4A  due to temperature rise or moisture absorption. How much the LCD protection panel  13  extends due to the expansion resulting from moisture absorption varies depending on water absorption, a panel thickness, etc. If the LCD protection panel  13  is made of, for example, polymethyl methacrylate (PMMA) as an acrylic polymer, the water absorption is 0.3%. 
         [0016]    On the other hand, as described above, the outer edge of the lower surface of the LCD protection panel  13  is fixed onto the liquid crystal display protection panel mounting surface  11   a  through the double-faced adhesive tape  14 . Further, there is no space but a small gap resulting from dimensional tolerances, between the end face of the LCD panel protection  13  and the inner surface of the upper portion of the front case  11 . 
         [0017]    Therefore, although the LCD protection panel  13  tends to expand due to temperature rise or moisture absorption, the extension in a horizontal direction (direction of the arrow of  FIG. 4A ) resulting from the expansion is restricted. 
         [0018]    As a result, as shown in  FIG. 4B , the LCD protection panel  13  warps inwardly (downwardly in  FIG. 4B ) according to the expansion, and the lower surface of the LCD protection panel  13  comes into contact (interferes) with the upper surface of the LCD panel  18  in some cases. If the lower surface of the LCD protection panel  13  comes into contact with the upper surface of the LCD panel  18 , the contact portion looks like a droplet infiltrated in a space between the LCD protection panel  13  and LCD panel  18 . As a result, there is no choice but to repair the liquid crystal display device  9 . 
         [0019]    One conceivable countermeasure against such a problem is to secure enough space between the lower surface of the LCD protection panel  13  and the upper surface of the LCD panel  18  not to bring the lower surface of the LCD protection panel  13  and the upper surface of the LCD panel  18  into contact with each other even if the LCD protection panel  13  expands. However, this structure leads to enlargement of the liquid crystal display device  9  and thus the cell phone  10 . 
       SUMMARY 
       [0020]    According to an aspect of an embodiment, a liquid crystal device comprises a liquid crystal display panel, a liquid crystal display protection panel protecting a display surface of the liquid crystal display panel, and a frame supporting the liquid crystal display protection panel on a periphery of a surface of the liquid crystal display protection panel, wherein a gap is installed between a edge surrounding the liquid crystal display protection panel and the frame. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a front view of a conventional cell phone equipped with a liquid crystal display device; 
           [0022]      FIG. 2  is a cross-sectional view of the liquid crystal display device of  FIG. 1 ; 
           [0023]      FIG. 3  is an enlarged view of a portion A enclosed by the dotted line of  FIG. 2 ; 
           [0024]      FIGS. 4A and 4B  are sectional views illustrating problems of the conventional liquid crystal display device; 
           [0025]      FIG. 5  is a perspective view of a cell phone equipped with a liquid crystal display device according to a first embodiment; 
           [0026]      FIG. 6  is a cross-sectional view of the liquid crystal display device of  FIG. 5 ; 
           [0027]      FIGS. 7A and 7B  show how a liquid crystal display protection panel of  FIG. 6  expands; and 
           [0028]      FIG. 8  is an enlarged view of a modified example of a portion A enclosed by the dotted line of  FIG. 6 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0029]    Hereinafter, embodiments will be described. 
         [0030]      FIG. 5  is a perspective view of a cell phone equipped with a liquid crystal display device according to a first embodiment. 
         [0031]    A cell phone  20  of  FIG. 5  includes a stationary-side case  21  and a movable-side case  23  coupled with the stationary-side case  21  through a hinge  22  in a foldable manner. In the illustrated example of  FIG. 5 , the movable-side case  23  of the cell phone  20  is opened. 
         [0032]    The stationary-side case  21  has a flat, substantially rectangular shape. An inner surface  24  of the stationary-side case  21  is provided with, for example, plural push buttons  25 ,  26 , and  27 . Further, an inner surface  28  of the movable-side case  23  is provided with, for example, a liquid crystal display device  29 . 
         [0033]      FIG. 6  is a cross-sectional view of the liquid crystal display device  29  of  FIG. 5 . 
         [0034]    As shown in  FIG. 6 , the liquid crystal display device  29  includes an LCD (liquid crystal display) protection panel  33 , a frame  41  as a plate-like member bent at substantially right angle, a substrate  35 , a liquid crystal module holder  36 , liquid crystal modules  37  and  38  nested into a concave portion of the liquid crystal module holder  36 , and a dustproof gasket  39 . By the way, the liquid crystal module  38  is a liquid crystal display (LCD) panel, and the liquid crystal module  37  is a LCD panel holder for holding the LCD panel  38 . 
         [0035]    The LCD protection panel  33  is a panel for protecting a display surface of LCD panel  38 , and made of, for example, polymethyl methacrylate (PMMA) as an acrylic polymer. 
         [0036]    The frame  41  is composed of a liquid crystal display protection panel contact portion  41 a and a holder connection portion  41   b  extending from the liquid crystal display protection panel contact portion  41   a  and bent at substantially right angel to the liquid crystal display protection panel contact portion  41   a.  The liquid crystal display protection panel contact portion  41   a  is positioned over both ends of an upper surface of the LCD protection panel  33  and the vicinities thereof. The holder connection portion  41   b  is connected to the liquid crystal module holder  36  through engagement of claws (not shown) with holes (not shown) formed in the holder connection portion  41   b,  the claws being formed in corresponding positions on the liquid crystal module holder  36 . That is, the frame  41  presses the upper surface of the LCD protection panel  33  from above the LCD protection panel  33  while being connected to the liquid crystal module holder  36 . 
         [0037]    As described below in detail, both ends of the LCD protection panel  33  are positioned away from the inner surface of the holder connection portion  41   b  of the frame  41  by a predetermined length, for example, 0.2 mm. There is a gap T between the end portion of the LCD protection panel  33  and the inner surface of the holder connection portion  41   b  of the frame  41 . 
         [0038]    The thus-structured frame  41  is made of, for example, stainless steel (SAS). If a stainless steel (SAS)-made plate-like member is used for the frame  41 , the total thickness of the device can be reduced. Here, as long as the frame can press the upper surface of the LCD protection panel  33  from above the LCD protection panel  33 , a material for the frame  41  is not particularly limited. For example, a resin or magnesium alloy may be molded into the frame  41 . Further, it is possible to mold a resin or magnesium alloy into an armor and cover the frame  41  with the armor. 
         [0039]    The concave liquid crystal module holder  36  having a substrate  35  attached to the bottom is provided below the LCD protection panel  33 . The liquid crystal module holder  36  is made of, for example, stainless steel (SAS). Here, a material for the liquid crystal module holder  36  is not particularly limited, and a resin or magnesium alloy may be molded into the liquid crystal module holder  36 . 
         [0040]    Electronic components such as a chip capacitor are mounted onto the substrate  35  but are not illustrated in  FIG. 6 . The liquid crystal modules  37  and  38  are nested into the concave portion of the liquid crystal module holder  36 . 
         [0041]    The dustproof gasket  39  made of cushioning such as urethane form rubber is put on an upper edge of the LCD panel  38 . The dustproof gasket  39  is in contact with a lower surface of the LCD protection panel  33  and supports the lower surface of the LCD protection panel  33 . This structure protects the liquid crystal modules  37  and  38  from powder dust. 
         [0042]    The thus-structured LCD protection panel  33  tends to expand in the direction of the arrow of  FIG. 7A  due to temperature rise or moisture absorption.  FIGS. 7A and 7B  are sectional views similar to  FIG. 6 . The outer edge of the lower surface of the LCD protection panel  33  is not fixed by a double-faced adhesive tape  14  (see  FIG. 2 ), and both ends of the LCD protection panel  33  are away from the inner surface of the holder connection portion  41   b  of the frame  41 , so the extension of the LCD protection panel  33  in a horizontal direction (direction of the arrow of  FIG. 7A ) is not restricted. Accordingly, this expansion can be absorbed in a planar direction, and the LCD protection panel  33  does not warp even if expanded. 
         [0043]    In other words, the gap T between the end portion of the LCD protection panel  33  and the inner surface of the holder connection portion  41   b  of the frame  41  is large enough to keep a space between the end portion of the LCD protection panel  33  and the inner surface of the holder connection portion  41   b  of the frame  41  even after the LCD protection panel  33  expands in a horizontal direction (direction of the arrow of  FIG. 7A ). Thus, even if the LCD protection panel  33  expands, the degree of freedom of extension in a width direction of the LCD protection panel  33  is secured, so the end portions of the expanded LCD protection panel can extend in the width direction (direction of the arrow of  FIG. 7A ). 
         [0044]    As described above, in this embodiment, the device is structured such that the gap T is defined between the end portion of the LCD protection panel  33  and the inner surface of the holder connection portion  41   b  of the frame  41 , the dustproof gasket  39  supports the lower surface of the LCD protection panel  33 , and the liquid crystal display protection panel contact portion  41   a  of the frame  41  presses the upper surface of the LCD protection panel  33 . 
         [0045]    With this structure, the LCD protection panel  33  does not warp even if expanded. Hence, it is possible to keep the lower surface of the LCD protection panel  33  from contact (interfering) with the upper surface of the LCD panel  38 . 
         [0046]    Further, since the LCD protection panel  33  does not warp even if expanded, it is unnecessary to increase a gap S between the lower surface of the LCD protection panel  33  and the upper surface of the LCD panel  38 . Hence, it is unnecessary to enlarge the liquid crystal display device  29  and the cell phone  20 . 
         [0047]    In the illustrated example of  FIG. 6 , the liquid crystal display protection panel contact portion  41   a  of the frame  41  is directly placed over both ends of the upper surface of the LCD protection panel  33  and the vicinities thereof. However, this embodiment is not limited thereto, and the structure of  FIG. 8  may be employed.  FIG. 8  is an enlarged view of a modified example of the portion A enclosed by the dotted line of  FIG. 6 . 
         [0048]    In  FIG. 8 , for example, the liquid crystal display protection panel contact portion  41   a  of the frame  41  is placed over both ends of the upper surface of the LCD protection panel  33  and the vicinities thereof through a dustproof member  50 . 
         [0049]    A one-sided adhesive tape or cushioning may be used as the dustproof member  50 . By inserting the dustproof member  50  between the liquid crystal display protection panel contact portion  41   a  of the frame  41  and the LCD protection panel  33 , intrusion of power dust from the outside can be surely prevented. Further, if a one-sided adhesive tape or cushioning is used as the dustproof member  50 , for example, the following advantages can be attained in addition to the dustproof effect. That is, even if the LCD protection panel  33  expands, the extension of the LCD protection panel  33  in a horizontal direction (direction of the arrow of  FIG. 7A ) is not restricted, and the LCD protection panel  33  can be prevented from warping. 
         [0050]    As described above, according to the structure of this embodiment, the lower surface of the LCD protection panel  33  can be kept from contact (interfering) with the upper surface of the LCD panel  38 . Thus, it is possible to avoid a phenomenon that looks as if a droplet infiltrates in between the LCD protection panel  33  and the LCD panel  38  can be avoided without increasing the gap between the lower surface of the LCD protection panel  33  and the upper surface of the LCD panel  38 . 
         [0051]    The liquid crystal display device  29  is illustrated in  FIG. 6  in cross-section. However, this structure is also applicable to the longitudinal-section structure of the liquid crystal display device  29 . 
         [0052]    The embodiments are described in detail above. However, the present invention is not limited to the above embodiments but could be modified and changed without departing from the scope of the invention. 
         [0053]    For example, the above embodiments of the present invention describe the liquid crystal display device in the cell phone for illustrative purposes, but the present invention is also applicable to a liquid crystal display device in other electronic devices such as a portable information terminal such as a PDA (personal digital assistants), a portable PC (personal computer) such as a laptop PC, a desktop PC, and a television.