Abstract:
A display device includes: a rear frame having a bottom surface and a side surface, the side surface being provided with a female screw that projects outwardly; a flat light guide plate arranged inside the rear frame, the flat light guide plate receiving light from a light source to emit the same in a flat manner; a display panel opposed to the flat light guide plate, the display panel controlling the light emitted from the flat light guide plate to display an image; and a front frame with an opening facing the display panel, the front frame being provided with a fitting portion in the form of an aperture on its side surface, the fitting portion being fitted with the female screw which thereby forms a fixing member for fixation to an outer casing.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a fixing member of a display device. 
   2. Description of the Background Art 
   In recent years, a liquid crystal display (LCD) using a liquid crystal display panel has been widely used for various purposes for its lightness and thinness. 
   A liquid crystal display panel is formed by a glass substrate and a counter substrate provided with interconnect lines and electrodes. The glass substrate and the counter substrate are arranged in parallel, and liquid crystal is sandwiched between these substrates. Polarizing plates are attached to both surfaces of the liquid crystal display panel. A display area of the liquid crystal display panel is formed by a number of pixels. A signal is applied to each one of these pixels in accordance with a display image to thereby produce the image. Light emitted from a backlight system arranged on the back side of the liquid crystal display panel is applied to the display image, so that the image is visually recognized by a viewer. 
   That is, the liquid crystal display is a so-called light receiving display device including a liquid crystal display panel and a backlight system that control the light transmittance for each pixel. The liquid crystal display having these properties is widely applied for various purposes. By way of example, the liquid crystal display is employed as a display of a personal computer, or as a display device of equipment for commercial use. 
   For greater design flexibility of the liquid crystal display, size reduction of a frame except a display area is required to a minimum. In order to realize size reduction of the frame, a fixing member including a screw arranged on the side surface of the liquid crystal display is adopted to provide fixation to a casing. 
   An example of the liquid crystal display using the fixing member is introduced in Japanese Patent Application Laid-Open No. 2004-233849. 
   In one example of the liquid crystal display of the background art, a screw portion is provided at a rear frame. In this example, the screw portion is constructed in the form of a projection to enter a backlight system from the side surface of the rear frame. This requires space in the liquid crystal display to avoid the length of a screw to be inserted from the side surface, inhibiting size reduction of a frame. 
   In another example of the liquid crystal display of the background art that adopts a fixing member including a screw arranged on a side surface, a screw portion is provided at a front frame. In this example, the screw portion is constructed in the form of a projection to enter a backlight system from the side surface of the front frame. Then the screw portion is located near the outer periphery of a module, allowing space reduction. This however causes insufficient fixation of the backlight system stored in the module, failing to maintain sufficient strength. 
   SUMMARY OF THE INVENTION 
   It is an object of the present invention to provide a display device with a fixing member capable of realizing size reduction of a frame. 
   The present invention is intended for a display device including a rear frame, a flat light guide plate, a display panel and a front frame. The rear frame has a bottom surface and a side surface. The side surface is provided with a female screw that projects outwardly. The flat light guide plate is arranged inside the rear frame, and receives light from a light source to emit the same in a flat manner. The display panel is opposed to the flat light guide plate, and controls the light emitted from the flat light guide plate to display an image. The front frame has an opening facing the display panel. The front frame is provided with a fitting portion in the form of an aperture on its side surface. The fitting portion is fitted with the female screw which thereby forms a fixing member for fixation to an outer casing. 
   As the screw portion is located near the outer periphery of a module, fixation is realized by using a small screw. Thus the display device of the present invention realizes size reduction of a frame. 
   The present invention is also intended for a display device including a rear frame, a flat light guide plate, a middle frame, a display panel and a front frame. The rear frame has a bottom surface and a side surface. The flat light guide plate is arranged inside the rear frame, and receives light from a light source to emit the same in a flat manner. The middle frame is arranged inside the rear frame, and surrounds the flat light guide plate. The middle frame has a female screw on its side surface that projects outwardly. The display panel is opposed to the flat light guide plate, and is supported by the middle frame. The display panel controls the light emitted from the flat light guide plate to display an image. The front frame has an opening facing the display panel. The front frame is provided with a fitting portion in the form of an aperture on its side surface. The fitting portion is fitted with the female screw which thereby forms a fixing member for fixation to an outer casing. 
   A screw portion can be enlarged to thereby enhance a degree of shock resistance. 
   These and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is an exploded perspective view schematically showing the structure of a liquid crystal display according to a first preferred embodiment of the present invention; 
       FIG. 2  is a sectional view showing the structure of a fixing part of the liquid crystal display according to the first preferred embodiment; 
       FIG. 3  is a side view of a fitting portion of a front frame of the liquid crystal display shown in  FIG. 2 ; 
       FIG. 4  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a second preferred embodiment of the present invention; 
       FIG. 5  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a third preferred embodiment of the present invention; 
       FIG. 6  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a fourth preferred embodiment of the present invention; 
       FIG. 7  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a fifth preferred embodiment of the present invention; 
       FIG. 8  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a sixth preferred embodiment of the present invention; 
       FIG. 9  is a sectional view showing the structure of a fixing part of a liquid crystal display according to a seventh preferred embodiment of the present invention; and 
       FIGS. 10 to 12  are sectional views each showing the structure of a fixing part of a liquid crystal display of the background art. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   First Preferred Embodiment 
     FIG. 1  is an exploded perspective view schematically showing the structure of a liquid crystal display according to a first preferred embodiment of the present invention. In the following, the structure of the liquid crystal display will be discussed. 
   The liquid crystal display includes: a backlight system  10  with a light source  2  and a flat light guide plate  5 ; a liquid crystal display panel  1  arranged on the front side of the backlight system  10  and which controls the transmittance of light emitted from the backlight system  10 ; and a front frame  11  for storing the backlight system  10  and the liquid crystal display panel  1  and which has a fitting portion  11   a  in the form of an aperture on its side surface. 
   The liquid crystal display panel  1  includes an upper substrate  1   a  and a lower substrate  1   b . One of the upper substrate  1   a  and the lower substrate  1   b  is a TFT array substrate formed with a colored layer, a light shielding layer, a thin film transistor (hereinafter referred to as a TFT), an electrode such as a pixel electrode and an interconnect line. The other is an opposite substrate. The liquid crystal display panel  1  further includes: a spacer for maintaining uniform space between the two substrates; a sealing agent for bonding the two substrates together; a sealing material for providing sealing after liquid crystal is introduced between the two substrates; an orientation film for providing initial orientation of liquid crystal; polarization plates  1   c ,  1   d  for allowing only a specific polarization component of light emitted from the backlight system  10  to pass therethrough, and the like. 
   The flat light guide plate  5  includes an optical sheet  6  and a reflective plate  4 . A light incident plane  5   a  is arranged to face the light source  2 . A light exit plane  5   b  is arranged substantially perpendicular to the light incident plane  5   a . A plane  5   c  facing the light exit plane  5   b  is provided with a printed dot pattern  5   d  for disturbing a direction of light propagation. The flat light guide plate  5  is formed by an acrylic material, a polycarbonate material or a transparent body such as glass. Instead of providing the printed dot pattern  5   d  on the plane  5   c , the light exit plane  5   b  or the plane  5   c  may be roughened. The light exit plane  5   b  or the plane  5   c  may alternatively be an uneven surface formed for example by small spherical surfaces or prism for varying a direction of light propagation. 
   The optical sheet  6  is a diffusion sheet arranged near the light exit plane  5   b  of the flat light guide plate  5 . The optical sheet  6  may be formed by a plurality of sheets. Alternatively, the optical sheet  6  may be a prism sheet, or further alternatively, an optical sheet is not necessarily required. The reflective plate  4  is arranged near the flat light guide plate  5  except for the light incident plane  5   a  and the light exit plane  5   b . The reflective plate  4  is formed by a diffusion reflective material with reflectivity of 90% or higher. The reflective plate  4  may alternatively be a silver-evaporated sheet for realizing regular reflection. 
   Next, a light source unit  9  will be discussed that includes the light source  2 , a reflector  8  and the like. The light source  2  is covered with the reflector  8 , and is formed by a lamp. The light source  2  may alternatively be a lineup of light sources such as LEDs. The reflector  8  serves to reflect light emitted from the light source  2  to allow the reflected light to enter the light incident plane  5   a . The reflector  8  is formed by a diffusion reflective material with reflectivity of 90% or higher and a metal plate that are bonded together. The reflector  8  may alternatively be formed by a silver-evaporated sheet for realizing regular reflection and a material for realizing polarized reflection that are bonded together. Still alternatively, the reflector  8  may be formed by a coated material or a mirror-finished material. 
     FIG. 2  is a sectional view showing the structure of a fixing part of the liquid crystal display shown in  FIG. 1  according to the first preferred embodiment. The liquid crystal display includes a middle frame  7  for supporting the liquid crystal display panel  1  on the flat light guide plate  5 , and a metal rear frame  3  having a screw hole for fixation. The screw hole has a screw projection  13  that projects outwardly of the light guide plate  5  from a side surface  3   a  of the rear frame  3 . 
   The screw projection  13  is formed integrally with the rear frame  3 , and is in the form of a burr  13  that projects outwardly from the side surface  3   a . A screw portion  12  used for fixation is provided inside the burr  13 . The screw projection  13  in the form of a burr is fitted with the fitting portion  11   a  formed in the front frame  11  to thereby make positioning of the backlight system  10  and the front frame  11 . A screw  19  is threadedly engaged with the screw portion  12  to thereby form a fixing member that realizes fixation to an outer casing  20 . The liquid crystal display panel  1  is supported by the middle frame  7 . The middle frame  7  is fixed by the rear frame  3  and the front frame  11  to thereby fix the liquid crystal display panel  1 . 
     FIGS. 10 to 12  are sectional views each partially showing a liquid crystal display using a fixing part of the background art. In each of the liquid crystal displays shown in  FIGS. 10 and 11 , the screw portion  12  is formed so as to project toward a backlight system from the side surface  3   a  of the rear frame  3 . Space  18  for avoiding the length of the screw  19  is defined inside the liquid crystal display. In the liquid crystal display shown in  FIG. 12 , the screw portion  12  is formed so as to project toward a backlight system from the side surface of the front frame  11 , thereby fixing the screw portion  12  to the external casing  20 . 
   As discussed, in the liquid crystal display of the background art, the burr  13  of the metal rear frame  3  and the space  18  for avoiding a screw to be inserted for fixation of a module are provided to the middle frame  7 . In contrast, according to the present invention, the burr  13  projects outwardly, so that the screw portion  12  is allowed to be close to the outer periphery of a module. This allows reduction or elimination of space for the middle frame  7 , thereby obtaining a liquid crystal display that realizes a greater degree of size reduction of a frame. The burr  13  and the front frame  11  are fitted together to make positioning of the screw portion  12  and the front frame  11  without requiring an additional positioning mechanism. 
   In the structure shown in  FIG. 2 , the fitting portion  11   a  of the front frame  11  is in the shape of a hook that is in contact in part with the burr  13  to support the liquid crystal display panel  1 . The fitting portion  11   a  may alternatively be a notch  11   b  as shown in the side view of the screw portion  12  illustrated in  FIG. 3 . In this case, positioning may be made only in a direction of the plane of the liquid crystal display panel  1 . 
   Second Preferred Embodiment 
     FIG. 4  is a sectional view partially showing a liquid crystal display according to a second preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the second preferred embodiment includes a middle frame  7  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 , and a metal rear frame  3  having a screw hole for fixation. The screw hole has a screw projection  14   a  that projects outwardly of the flat light guide plate  5  from a side surface  3   a  of the rear frame  3 . 
   The screw projection  14   a  is a nut  14  joined with the side surface  3   a  of the rear frame  3 . A screw portion  12   a  used for fixation is provided inside the nut  14 . The screw projection  14   a  formed by the nut  14  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   The use of the nut  14  allows the screw portion  12   a  and the screw projection  14   a  to be different in material and thickness from the rear frame  3 . Thus the screw portion  12   a  and the screw projection  14   a  are allowed to have an enhanced degree of shock resistance. 
   Third Preferred Embodiment 
     FIG. 5  is a sectional view partially showing a liquid crystal display according to a third preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the third preferred embodiment includes a plastic rear frame  3  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 . The rear frame  3  has a screw hole for fixation. The screw hole has a screw projection  15   a  that projects outwardly of the flat light guide plate  5  from a side surface  3   a  of the rear frame  3 . 
   The screw projection  15   a  is a nut  15  joined with the side surface  3   a  of the rear frame  3 . A screw portion  12   b  used for fixation is provided inside the nut  15 . The screw projection  15   a  formed by the nut  15  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The liquid crystal display panel  1  is supported by the rear frame  3 . The rear frame  3  and the front frame  11  are fixed to thereby fix the liquid crystal display panel  1 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   The nut  15  is joined with the plastic rear frame  3 . Thus, as compared to the joining with a metal rear frame, the screw portion  12   b  of the nut  15  can be enlarged. As a result, the screw portion  12   b  is allowed to have an enhanced degree of shock resistance. 
   Fourth Preferred Embodiment 
     FIG. 6  is a sectional view partially showing a liquid crystal display according to a fourth preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the fourth preferred embodiment includes a plastic rear frame  3  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 . The rear frame  3  has a screw hole for fixation. The screw hole has a screw projection  16  that projects outwardly of the flat light guide plate  5  from a side surface  3   a  of the rear frame  3 . 
   The screw projection  16  is the rear frame  3  projecting outwardly of the flat light guide plate  5 . A screw portion  12   c  used for fixation is provided inside a nut  15  that is joined with the side surface  3   a  of the rear frame  3 . The screw projection  16  formed by the rear frame  3  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   Thus the screw projection  16  fitted with the front frame  11  is allowed to have an arbitrary shape, so that fitting with the front frame  11  can be easily realized. 
   Fifth Preferred Embodiment 
     FIG. 7  is a sectional view partially showing a liquid crystal display according to a fifth preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the fifth preferred embodiment includes a plastic rear frame  3  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 . The rear frame  3  has a screw hole  16   a  for fixation. The screw hole  16   a  has a screw projection  17  that projects outwardly of the flat light guide plate  5  from a side surface  3   a  of the rear frame  3 . 
   The screw projection  17  is the rear frame  3  projecting outwardly of the flat light guide plate  5 . The screw hole  16   a  provided to the rear frame  3  serves as a pilot hole for a tapping screw used for fixation. The screw projection  17  formed by the rear frame  3  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   Thus the screw projection  17  fitted with the front frame  11  is allowed to have an arbitrary shape, so that fitting with the front frame  11  can be easily realized. Further, the liquid crystal display can be provided at a low cost without requiring an additional component such as a nut. 
   Sixth Preferred Embodiment 
     FIG. 8  is a sectional view partially showing a liquid crystal display according to a sixth preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the sixth preferred embodiment includes a plastic middle frame  7  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 . The middle frame  7  has a screw hole for fixation. The screw hole has a screw projection  15   a  that projects outwardly of the flat light guide plate  5  from a side surface  7   a  of the middle frame  7 . 
   The screw projection  15   a  is a nut  15  joined with the side surface  7   a  of the middle frame  7 . A screw portion  12   d  used for fixation is provided inside the nut  15 . The screw projection  15   a  formed by the nut  15  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   The nut  15  is joined with the plastic middle frame  7 . Thus, as compared to the joining with a metal rear frame  3 , the screw portion  12   d  of the nut  15  can be enlarged. As a result, the screw portion  12   d  is allowed to have an enhanced degree of shock resistance. 
   Seventh Preferred Embodiment 
     FIG. 9  is a sectional view partially showing a liquid crystal display according to a seventh preferred embodiment of the present invention. Differences from the first preferred embodiment will be discussed. The liquid crystal display of the seventh preferred embodiment includes a plastic middle frame  7  for supporting a liquid crystal display panel  1  on a flat light guide plate  5 . The middle frame  7  has a screw hole for fixation. The screw hole has a screw projection  17  that projects outwardly of the flat light guide plate  5  from a side surface  7   a  of the middle frame  7 . 
   The screw projection  17  is the middle frame  7  projecting outwardly of the flat light guide plate  5 . The screw hole provided to the middle frame  7  serves as a pilot hole for a tapping screw used for fixation. The screw projection  17  formed by the middle frame  7  is fitted with a fitting portion  11   a  formed in a front frame  11  to thereby make positioning of a backlight system  10  and the front frame  11 . The other structures are the same as those of the first preferred embodiment, and will not be discussed again. 
   Thus the screw projection  17  fitted with the front frame  11  is allowed to have an arbitrary shape, so that fitting with the front frame  11  can be easily realized. Further, the liquid crystal display can be provided at a low cost without requiring an additional component such as a nut. Like the structure shown in  FIG. 2 , if the screw projection  17  is constructed in the shape of a burr formed integrally with the middle frame  7 , the same effect as in the first preferred embodiment can be produced. 
   As in the first preferred embodiment, in the second through seventh preferred embodiments, the fitting portion  11   a  of the front frame  11  may also be in the shape of a hook as shown in  FIG. 3 . In this case, positioning may be made only in a direction of the plane of the liquid crystal display panel  1 . 
   While the invention has been shown and described in detail, the foregoing description is in all aspects illustrative and not restrictive. It is therefore understood that numerous modifications and variations can be devised without departing from the scope of the invention.