Abstract:
A light guide plate (LGP) includes a positioning block that includes a positioning block body and a liquid filled and hermetically sealed in a receiving compartment formed in the interior of the positioning block body. The liquid is expandable with a drop of temperature so as to increase a volume thereof and thus enlarge a size of the positioning block body through elasticity of the positioning block body. In this way, the LGP positioning block is adjustable with the variation of the surrounding temperature so as to achieve effective positioning of the light guide plate and providing high reliability of a liquid crystal display device including the light guide plate.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This is a continuation application of co-pending patent application Ser. No. 14/429,067, filed on Mar. 18, 2015, which is a national stage of PCT Application Number PCT/CN2015/072561, filed on Feb. 9, 2015, claiming foreign priority of Chinese Patent Application Number 201410842588.5, filed on Dec. 30, 2014. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to the field of displaying technology, and in particular to a liquid crystal display device and a method for manufacturing a light guide plate (LGP) positioning block thereof. 
         [0004]    2. The Related Arts 
         [0005]    Liquid crystal displays (LCDs) have a variety of advantages, such as thin device body, low power consumption, and being free of radiation, and are thus used widely, such as mobile phones, personal digital assistants (PDAs), digital cameras, computer monitors, and notebook computer screens. 
         [0006]    Most of the LCDs that are currently available in the market are backlighting LCDs, which comprise an enclosure, a liquid crystal panel arranged in the enclosure, and a backlight module mounted in the enclosure. Since the liquid crystal panel is not self-luminous, light supplied from the backlight module is necessary for normally displaying an image. Thus, the backlight module is one of the key components of a liquid crystal display. The backlight modules can be classified as a side-edge backlight module and a direct backlight module, according to the site where light gets incident. The direct backlight module comprises a light source, such as a cold cathode fluorescent lamp (CCFL) or a light-emitting diode (LED), which is arranged at the backside of the liquid crystal panel to directly form a planar light source supplied to the liquid crystal panel. The side-edge backlight module comprises an LED light bar, serving as a backlight source, which is arranged at an edge of a backplane to be located rearward of one side of the liquid crystal panel. The LED light bar emits light that enters a light guide plate (LGP) through a light incident face at one side of the light guide plate and is projected out of a light emergence face of the light guide plate, after being reflected and diffused, to pass through an optic film assembly so as to form a planar light source for the liquid crystal panel. 
         [0007]    The LGP is one of the important components of a liquid crystal display and is often made of poly(methyl methacrylate) (PMMA), which is also referred to as “organic glass” and has the property of thermal expansion. When a liquid crystal display is operating in a high temperature, the LGP gets expanded; and for operation in a low temperature, the LGP contracts. The size difference between expanding and contracting might as large as millimeters. On the other hand, positional accuracy between the LGP and the backlight source affects, to a great extent, the image style of the liquid crystal display. 
         [0008]      FIG. 1  is an exploded view showing a conventional liquid crystal display device and  FIG. 2  is a top plan view showing a backlight module of the conventional liquid crystal display device. With reference to  FIGS. 1 and 2 , the conventional liquid crystal display device comprises a backlight module  10  that is composed of a backplane  100 , a light-emitting diode (LED) light bar  200 , a light guide plate  300 , and an optic film assembly  400 , a mold frame  500  arranged on the backlight module  10 , a liquid crystal panel  600  arranged on the mold frame  500 , and a bezel  700  arranged on the liquid crystal panel  600 . The light guide plate  300  comprises positioning posts  800  arranged adjacent to a light-entrance side of the LED light bar  200  to maintain a light coupling distance between the light guide plate  300  and the LED light bar  200 , while elastic positioning blocks  900  are arranged at the side of the light guide plate  300  that is distant from the LED light bar  200  to achieve positioning. 
         [0009]    As shown in  FIG. 3 , in a normal temperature, a proper gap is present between the side of the light guide plate  300  that is distant from the LED light bar  200  and the positioning blocks  900  to facilitate assembly and accommodate manufacturing tolerances. 
         [0010]    As shown in  FIG. 4 , when the liquid crystal display device is in a high temperature, the light guide plate  300  that is heated and thus expanded gets into contact with the positioning blocks  900 . Since the positioning blocks  900  are made of a solid elastic material and thus possess elasticity, they can absorb the increased size of the light guide plate  300  caused by expansion so as to maintain stable and tight engagement between the light guide plate  300  and the positioning blocks  900 . 
         [0011]    However, as shown in  FIG. 5 , when the liquid crystal display device is in a low temperature, the light guide plate  300  is cooled and gets contracted so that the gap between the light guide plate  300  and the positioning blocks  900  is enlarged. Under this condition, the positioning blocks  900  do not provide the function of effective positioning so that the light guide plate  300  may readily separate and break due to actions caused by vibrations and impacts. 
       SUMMARY OF THE INVENTION 
       [0012]    An object of the present invention is to provide a liquid crystal display device, which has light guide plate (LGP) positioning block that is adjustable with variation of the surrounding temperature so as to achieve effective positioning of an LGP, thereby providing the liquid crystal display device with high reliability and stable taste of displayed images. 
         [0013]    Another object of the present invention is to provide a method for manufacturing an LGP positioning block of a liquid crystal display device, wherein an LGP positioning block manufactured with such a method is adjustable with variation of the surrounding temperature to achieve effective positioning of an LGP. 
         [0014]    To achieve the above objects, the present invention provides a liquid crystal display device, which comprises a backlight module, a mold frame arranged on the backlight module, a liquid crystal panel arranged on the mold frame, and a bezel arranged on the liquid crystal panel; 
         [0015]    wherein the backlight module comprises a backplane, a light-emitting diode (LED) light bar arranged in the backplane, a light guide plate (LPG) arranged in the backplane, an optic film assembly arranged on the light guide plate, and a positioning post and an LGP positioning block that position the light guide plate; and 
         [0016]    the LGP positioning block comprises a positioning block body and liquid hermetically sealed inside the positioning block body and the positioning block body possesses elasticity; 
         [0017]    whereby in a low temperature, the liquid gets condensed and expanded to enlarge a size of the positioning block body to compensate size reduction of the light guide plate caused by cooling; and in a high temperature, the elasticity of the positioning block body absorbs size expansion of the light guide plate caused by heating. 
         [0018]    The backplane comprises a bottom board and a side board perpendicularly connected to the bottom board, the LED light bar being mounted to the side board, the light guide plate comprising a light-entrance side and a non-light-entrance side distant from the light-entrance side, a light emission surface of the LED light bar opposing the light-entrance side of the light guide plate; and 
         [0019]    the positioning post is arranged at a location adjacent to the light-entrance side of the light guide plate to maintain a light coupling distance between the light guide plate and the LED light bar and the LGP positioning block is arranged on the bottom board between the side board and the LGP non-light-entrance side. 
         [0020]    The number of the positioning post used is two and the two positioning posts are arranged adjacent to the light-entrance side of the light guide plate and are opposite to each other; and the number of the LGP positioning block used is two and the two LGP positioning blocks are arranged opposite to each other and respectively set at corners of the LGP non-light-entrance side. 
         [0021]    The positioning block body comprises a sealing trough formed by recessing a surface thereof, a passageway in communication with the sealing trough and extending into the interior of the positioning block body, and a receiving compartment in communication with the passageway and formed in the interior of the positioning block body; and the liquid is filled in the receiving compartment and the passageway and the sealing trough seals the liquid. 
         [0022]    The sealing trough receives sealing adhesive filled therein and the sealing adhesive seals the liquid. 
         [0023]    The liquid comprises distilled water. 
         [0024]    The positioning block body is made of a material of rubber. 
         [0025]    The present invention also provides a method for manufacturing an LGP positioning block of a liquid crystal display device, which comprises the following steps: 
         [0026]    (1) providing a positioning block body; 
         [0027]    wherein the positioning block body possesses elasticity and comprises a sealing trough formed by recessing a surface thereof, a passageway in communication with the sealing trough and extending into the interior of the positioning block body, and a receiving compartment in communication with the passageway and formed in the interior of the positioning block body; 
         [0028]    (2) providing liquid and filling the liquid in the passageway and the receiving compartment; 
         [0029]    (3) applying sealing adhesive in the sealing trough; and 
         [0030]    (4) leveling and solidifying the sealing adhesive so that the sealing adhesive seals the liquid in the positioning block body to thereby complete the manufacture of the LGP positioning block. 
         [0031]    The liquid comprises distilled water. 
         [0032]    The positioning block body is made of a material of rubber. 
         [0033]    The present invention further provides a method for manufacturing an LGP positioning block of a liquid crystal display device, which comprises the following steps: 
         [0034]    (1) providing a positioning block body; 
         [0035]    wherein the positioning block body possesses elasticity and comprises a sealing trough formed by recessing a surface thereof, a passageway in communication with the sealing trough and extending into the interior of the positioning block body, and a receiving compartment in communication with the passageway and formed in the interior of the positioning block body; 
         [0036]    (2) providing liquid and filling the liquid in the passageway and the receiving compartment; 
         [0037]    (3) applying sealing adhesive in the sealing trough; and 
         [0038]    (4) leveling and solidifying the sealing adhesive so that the sealing adhesive seals the liquid in the positioning block body to thereby complete the manufacture of the LGP positioning block; 
         [0039]    wherein the liquid comprises distilled water; and 
         [0040]    wherein the positioning block body is made of a material of rubber. 
         [0041]    The efficacy of the present invention is that the present invention provides a liquid crystal display device, which comprises an LGP positioning block that comprises an elastic positioning block body and liquid hermetically sealed in the interior of the positioning block body. In a low temperature, the liquid gets condensed and expanded so as to enlarge the size of the positioning block body to compensate the size reduction of the light guide plate due to contraction caused by cooling; and in a high temperature, the elasticity of the positioning block body absorbs the size expansion of the light guide plate caused by heating so as to achieve adjustability of the LGP positioning block with temperature variation and allow for effective positioning of the light guide plate, thereby providing the liquid crystal display device with high reliability and stable taste of displayed images. The present invention also provides a method for manufacturing an LGP positioning block of a liquid crystal display device, in which liquid is first filled into the interior of a positioning block body, followed by application and solidification of the sealing adhesive to hermetically seal the liquid in the interior of the positioning block bod. The LGP positioning block manufactured with such a method allows for adjustability with variation of the surrounding temperature to achieve effective positioning of the light guide plate. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0042]    The technical solution, as well as other beneficial advantages, of the present invention will be apparent from the following detailed description of embodiments of the present invention, with reference to the attached drawing. In the drawing: 
           [0043]      FIG. 1  is an exploded view of a conventional liquid crystal display device; 
           [0044]      FIG. 2  is a top plan view of a backlight module of the conventional liquid crystal display device; 
           [0045]      FIG. 3  is an enlarged view showing an engagement site between a light guide plate and a positioning block of  FIG. 2  in a normal temperature; 
           [0046]      FIG. 4  is an enlarged view showing the engagement site between the light guide plate and the positioning block of  FIG. 2  in a high temperature; 
           [0047]      FIG. 5  is an enlarged view showing the engagement site between the light guide plate and the positioning block of  FIG. 2  in a low temperature; 
           [0048]      FIG. 6  is a cross-sectional view showing the structure of a liquid crystal display device according to the present invention in a normal temperature; 
           [0049]      FIG. 7  is a cross-sectional view showing the structure of the liquid crystal display device according to the present invention in a low temperature; 
           [0050]      FIG. 8  is a top plan view showing a backlight module of the liquid crystal display device according to the present invention; 
           [0051]      FIG. 9  is a flow chart illustrating a method for manufacturing a light guide plate positioning block of a liquid crystal display device according to the present invention; 
           [0052]      FIG. 10  is a schematic view illustrating step  1  of the method for manufacturing a light guide plate positioning block of a liquid crystal display device according to the present invention; 
           [0053]      FIG. 11  is a schematic view illustrating step  2  of the method for manufacturing a light guide plate positioning block of a liquid crystal display device according to the present invention; 
           [0054]      FIG. 12  is a schematic view illustrating step  3  of the method for manufacturing a light guide plate positioning block of a liquid crystal display device according to the present invention; and 
           [0055]      FIG. 13  is a schematic view illustrating step  4  of the method for manufacturing a light guide plate positioning block of a liquid crystal display device according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0056]    To further expound the technical solution adopted in the present invention and the advantages thereof, a detailed description is given to a preferred embodiment of the present invention and the attached drawings. 
         [0057]    Referring collectively to  FIGS. 6-8 , firstly, the present invention provides a liquid crystal display device. The liquid crystal display device comprises a backlight module  20 , a mold frame  5  arranged on the backlight module  20 , a liquid crystal panel  6  arranged on the mold frame  5 , and a bezel  7  arranged on the liquid crystal panel  6 . 
         [0058]    The backlight module  20  comprises a backplane  1 , a light-emitting diode (LED) light bar  2  arranged in the backplane  1 , a light guide plate (LPG)  3  arranged in the backplane  1 , an optic film assembly  4  arranged on the light guide plate  3 , and a positioning post  8  and an LGP positioning block  9  that position the light guide plate  3 . 
         [0059]    Further, the LGP positioning block  9  comprises a positioning block body  91  and liquid  93  hermetically sealed inside the positioning block body  91 . The positioning block body  91  is made of an elastic material, such as rubber, so that the positioning block body  91  possesses elasticity. The liquid  93  has the characteristics of being condensed when cooled down and thus increasing the volume thereof, and preferably, the liquid  93  is distilled water. Specifically, the positioning block body  91  comprises a sealing trough  912  formed by recessing a top surface thereof, a passageway  913  in communication with the sealing trough  912  and extending into the interior of the positioning block body  91 , and a receiving compartment  914  in communication with the passageway  913  and formed in the interior of the positioning block body  91 . The liquid  93  is filled in the receiving compartment  914  and the passageway  913 , while the sealing trough  912  is filled with sealing adhesive  915  so that the liquid  93  is sealed by the sealing adhesive  915 . 
         [0060]    The backplane  1  comprises a bottom board  11  and a side board  12  perpendicularly connected to the bottom board  11 . The LED light bar  2  is mounted to the side board  12 . The light guide plate  3  comprises a light-entrance side  31  and a non-light-entrance side  33  distant from the light-entrance side  31 . A light emission surface of the LED light bar  2  is opposing the light-entrance side  31  of the light guide plate  3 . 
         [0061]    The positioning post  8  is arranged at a location adjacent to the light-entrance side  31  of the light guide plate  3  to maintain a light coupling distance between the light guide plate  3  and the LED light bar  2 . The LGP positioning block  9  is arranged on the bottom board  11  between the side board  12  and the LGP non-light-entrance side  33 . Specifically, as shown in  FIG. 8 , the number of the positioning post  8  used is two and the two positioning posts  8  are arranged adjacent to the light-entrance side  31  of the light guide plate  3  and are opposite to each other. The number of the LGP positioning block  9  used is two and the two LGP positioning blocks  9  are arranged opposite to each other and respectively set at corners of the LGP non-light-entrance side  33 . 
         [0062]    As shown in  FIG. 6 , when the liquid crystal display device is in a normal temperature of around 25° C., a gap is present between the LGP positioning block  9  and the light guide plate  3  to facilitate assembly and to accommodate manufacturing tolerance. As shown in  FIG. 7 , in a low temperature lower than 0° C. down to −20° C., the liquid  93  is cooled and condensed and thus expanded so that the volume thereof is increased, whereby the size of the positioning block body  91  is enlarged to compensate the reduction of the size of the light guide plate  3  due to contraction caused by cooling. In a temperature higher than 50° C., such as a high temperature of 60° C., the liquid  93  may have very little expansion so that the elasticity of the positioning block body  91  may be sufficient to absorb the size expansion of the light guide plate  3  caused by heating. Thus, adjustability of the LGP positioning block  9  with temperature variation can be achieved to provide effective positioning of the light guide plate  3 , thereby achieving high reliability of the liquid crystal display device and stable taste of displayed image. 
         [0063]    Referring to  FIGS. 9-13 , the present invention also provides a method for manufacturing the above-described LGP positioning block of the liquid crystal display device, which comprises the following steps: 
         [0064]    Step 1: as shown in  FIG. 10 , providing a positioning block body  91 . 
         [0065]    The positioning block body  91  is made of an elastic material, such as rubber, so that the positioning block body  91  possesses elasticity. Specifically, the positioning block body  91  comprises a sealing trough  912  formed by recessing a top surface thereof, a passageway  913  in communication with the sealing trough  912  and extending into the interior of the positioning block body  91 , and a receiving compartment  914  in communication with the passageway  913  and formed in the interior of the positioning block body  91 . 
         [0066]    Step 2: as shown in  FIG. 11 , providing liquid  93  and filling the liquid  93  in the passageway  913  and the receiving compartment  914 . 
         [0067]    The liquid  93  has the characteristics of being condensed when cooled down and thus increasing the volume thereof, and preferably, the liquid  93  is distilled water. 
         [0068]    Step 3: as shown in  FIG. 12 , applying sealing adhesive  915  in the sealing trough  912 . 
         [0069]    Step 4: as shown in  FIG. 13 , leveling and solidifying the sealing adhesive  915  so that the sealing adhesive  915  seals the liquid  93  in the positioning block body  91  to thereby complete the manufacture of the LGP positioning block  9 . 
         [0070]    In the method for manufacturing above-described LGP positioning block of liquid crystal display device, the liquid  93  is first filled in the interior of the positioning block body  91 , followed by application and solidification of the sealing adhesive  915  to seal the liquid  93  in the interior of the positioning block body  91 . The LGP positioning block  9  manufactured with such a method is characterized in that in a low temperature, the liquid  93  is cooled down, condensed, and expanded so that the volume thereof is increased, making the size of the positioning block body  91  enlarged to compensate the size reduction of the light guide plate due to contraction caused by cooling; in a high temperature, the elasticity of the positioning block body  91  absorbs the size expansion of the light guide plate caused by heating so as to achieve adjustability of the LGP positioning block  9  with temperature variation and allow for effective positioning of the light guide plate  3 . 
         [0071]    In summary, the present invention provides a liquid crystal display device, which comprises an LGP positioning block that comprises an elastic positioning block body and liquid hermetically sealed in the interior of the positioning block body. In a low temperature, the liquid gets condensed and expanded so as to enlarge the size of the positioning block body to compensate the size reduction of the light guide plate due to contraction caused by cooling; and in a high temperature, the elasticity of the positioning block body absorbs the size expansion of the light guide plate caused by heating so as to achieve adjustability of the LGP positioning block with temperature variation and allow for effective positioning of the light guide plate, thereby providing the liquid crystal display device with high reliability and stable taste of displayed images. The present invention also provides a method for manufacturing an LGP positioning block of a liquid crystal display device, in which liquid is first filled into the interior of a positioning block body, followed by application and solidification of the sealing adhesive to hermetically seal the liquid in the interior of the positioning block bod. The LGP positioning block manufactured with such a method allows for adjustability with variation of the surrounding temperature to achieve effective positioning of the light guide plate. 
         [0072]    Based on the description given above, those having ordinary skills of the art may easily contemplate various changes and modifications of the technical solution and technical ideas of the present invention and all these changes and modifications are considered within the protection scope of right for the present invention.