Abstract:
A display apparatus for displaying an image, including: a liquid-crystal panel which displays the image; a back light which emits light toward a rear face of the liquid-crystal panel; a rear frame which supports the back light via a screw; and a rear cover which covers part of a face of the rear frame which is different from a face of the rear frame on which the back light is provided, wherein the back light extends beyond an inner-frame region of the rear frame covered by the rear cover, and the screw is provided only in the inner-frame region.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on and claims priority of Japanese Patent Application No. 2012-283624 filed on Dec. 26, 2012. The entire disclosure of the above-identified application, including the specification, drawings and claims is incorporated herein by reference in its entirety. 
       FIELD 
       [0002]    The present invention relates to display apparatuses for displaying images. 
       BACKGROUND 
       [0003]    There have conventionally been direct-backlit display devices, such as liquid-crystal television receivers and so on, which include back lights that emit light toward the rear face of a display panel (see Patent Literature (PTL) 1, for example). A housing of such a display device includes a resin-made front cabinet on the display panel side and a resin-made rear cabinet on the back light side. Furthermore, between the front cabinet and the rear cabinet, there is provided a rear frame for supporting back lights so as to allow heat conduction. The back lights include a heat sink, a wiring substrate joined to the heat sink, and a plurality of light emitting diodes (LEDs) mounted on the wiring substrate. The heat sink is fastened to the rear frame via a plurality of screws. 
         [0004]    The rear frame, the heat sink, and the wiring substrate are each formed of a metal having high heat conductivity (for example, aluminum or the like). When the LEDs each emit light, heat from the LED is transferred to the heat sink through the wiring substrate, and heat from the heat sink is transferred to the rear frame. By doing so, the heat from each of the LEDs is radiated through the heat sink and the rear frame. 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         [PTL 1] Japanese Unexamined Patent Application Publication No. 2007-311561 
       
     
       SUMMARY 
     Technical Problem 
       [0006]    In recent years, there is a demand for thinner display apparatuses with the aim of space saving. A conceivable method to meet the demand is to omit the above-stated rear cabinet, exposing part of the rear frame to outside the display device, for example. 
         [0007]    However, since the heat from each of the LEDs is transferred to the rear frame as mentioned above, the rear frame will have a relatively high temperature. For ensuring security when a user touches the rear frame, it is an objective to reduce the temperature rise inside the region of the rear frame exposed to outside the display apparatus. 
         [0008]    The present invention is devised to achieve the above objective and aims to provide a display apparatus in which the temperature rise inside the region of the rear frame exposed to outside can be reduced. 
       Solution to Problem 
       [0009]    In order to achieve the above object, a display apparatus according to an aspect of the present invention is a display apparatus for displaying an image, comprising: a display panel which displays the image; a back light which emits light toward a rear face of the display panel; a rear frame which supports the back light via a connecting part; and a rear cover which covers part of a face of the rear frame, the face being different from a face of the rear frame on which the back light is provided, wherein the back light extends beyond a covered region of the rear frame, the covered region being a region covered by the rear cover, and the connecting part is provided only in the covered region. 
         [0010]    Since part of the heat from the back lights is transferred to the rear frame through the connecting part, the rear frame has a relatively high temperature at the connecting part. According to this aspect, the connecting part which will have a relatively high temperature is provided only in the region of the rear frame covered by the rear cover, with the result that the temperature rise inside the region of the rear frame exposed to outside the display apparatus can be reduced. 
         [0011]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that the back light and the rear frame is spaced apart from each other outside the covered region. 
         [0012]    According to this aspect, the back light and the rear frame are spaced apart from each other, with the result that the heat transfer from the back light to outside the region of the rear frame covered by the rear cover can be blocked. With this, the temperature rise inside the region of the rear frame exposed to outside the display apparatus can be effectively reduced. 
         [0013]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that an inner face of the rear frame outside the covered region is positioned on a side of an inner face of the rear frame inside the covered region opposite a side on which the back light is positioned. 
         [0014]    According to this aspect, the inner face of the rear frame outside the region of the rear frame covered by the rear cover is positioned on the side of the inner face of the rear frame inside the region opposite the side on which the back light is positioned. With such a relatively simple configuration, the back light and the rear frame can be spaced apart from each other. 
         [0015]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that the back light and the rear frame have a heat insulating sheet therebetween outside the covered region. 
         [0016]    According to this aspect, the back light and the rear frame have a heat insulating sheet therebetween, with the result that the heat transfer from the back light to outside the region of the rear frame covered by the rear cover can be effectively blocked. 
         [0017]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that the back light includes: a heat sink supported by the rear frame and capable of conducting heat to the rear frame; a wiring substrate joined to the heat sink; and a light-emitting element mounted on the wiring substrate, and a transverse dimension of the heat sink outside the covered region is larger than a transverse dimension of the heat sink inside the covered region. 
         [0018]    According to this aspect, the transverse dimension of the heat sink outside the region of the rear frame covered by the rear cover is set to be relatively large, with the result that the heat radiation property of the heat sink outside the region can be enhanced. 
         [0019]    For example, in the display apparatus according to an aspect of the present invention, the rear frame may be configured so as to include a slit in part of a periphery of the connecting part which is located on an outer side inside the covered region. 
         [0020]    According to this aspect, the rear frame includes a slit in part of the periphery of the connecting part which is located on the outer side inside the region of the rear frame covered by the rear cover, with the result that the efficiency of heat transfer from the connecting part to outside the region is relatively low. With this, the temperature rise outside the above region of the rear frame can be effectively reduced. 
         [0021]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that the slit extends in an arc in the part of the periphery of the connecting part which is curved on the outer side inside the covered region. 
         [0022]    According to this aspect, the slit extends in an arc in part of the periphery of the connecting part such that the arc is curved on the outer side inside the region of the rear frame covered by the rear cover, with the result that the efficiency of heat transfer from the connecting part to outside the region of the rear frame can be effectively reduced. 
         [0023]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that the slit includes a bent edge portion bent toward the display panel or bent opposite from the display panel. 
         [0024]    According to this aspect, the slit includes the bent edge portion bent toward the display panel or bent opposite from the display panel, which can result in the slit of the rear frame having enhanced strength. 
         [0025]    For example, the display apparatus according to an aspect of the present invention may have a configuration such that a plurality of the back lights are provided, the back lights are arranged substantially parallel to each other, and a plurality of the connecting parts provided for the respective back lights are arranged in a staggered pattern. 
         [0026]    According to this aspect, the connecting parts are arranged in the staggered pattern, with the result that the temperature distribution inside the region of the rear frame covered by the rear cover can be substantially uniform. 
       Advantageous Effects 
       [0027]    With the present invention, it is possible to reduce the temperature rise inside the region of the rear frame exposed to outside the display apparatus. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]    These and other objects, advantages and features of the invention will become apparent from the following description thereof taken in conjunction with the accompanying drawings that illustrate a specific embodiment of the present invention. 
           [0029]      FIG. 1  is a perspective view showing, from the front side, a display apparatus according to Embodiment 1 of the present invention. 
           [0030]      FIG. 2  is a perspective view showing the display apparatus of  FIG. 1  from the rear side. 
           [0031]      FIG. 3  is a plan view showing the display apparatus of  FIG. 1  from the rear side. 
           [0032]      FIG. 4  is a plan view showing the interior of the display apparatus of  FIG. 1 . 
           [0033]      FIG. 5  is a main-part sectional view of the display apparatus taken along line A-A in  FIG. 4 . 
           [0034]      FIG. 6  is a main-part perspective view showing an exploded version of a back light. 
           [0035]      FIG. 7  is a plan view showing a magnified version of a slit and its surrounding area. 
           [0036]      FIG. 8  is a main-part perspective view showing a variation of the slit. 
           [0037]      FIG. 9  is a plan view showing the interior of a display apparatus according to Embodiment 2 of the present invention. 
           [0038]      FIG. 10  is a main-part sectional view of the display apparatus taken along line B-B in  FIG. 9 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0039]    Embodiments of the present invention will be described in detail below with reference to the drawings. It is to be noted that each of the embodiments described below indicates a preferred specific example of the present invention. The numerical values, shapes, materials, structural elements, the arrangement and connection of the structural elements, steps, the order of the steps etc. shown in the following embodiments are examples, and therefore do not intend to limit the present invention. The present invention is defined by the Claims. Therefore, among the structural elements in the following embodiments, structural elements not recited in any one of the independent claims are not necessarily required to achieve the objective of the present invention, but are described as elements which are included in more preferred embodiments. 
       Embodiment 1 
     [Configuration of Display Apparatus] 
       [0040]    Firstly, a display apparatus according to Embodiment 1 of the present invention is described with reference to  FIG. 1  to  FIG. 7 .  FIG. 1  is a perspective view showing, from the front side, the display apparatus according to Embodiment 1 of the present invention.  FIG. 2  is a perspective view showing the display apparatus of  FIG. 1  from the rear side.  FIG. 3  is a plan view showing the display apparatus of  FIG. 1  from the rear side.  FIG. 4  is a plan view showing the interior of the display apparatus of  FIG. 1 .  FIG. 5  is a main-part sectional view of the display apparatus taken along line A-A in  FIG. 4 .  FIG. 6  is a main-part perspective view showing an exploded version of a back light.  FIG. 7  is a plan view showing a magnified version of a slit and its surrounding area. 
         [0041]    A display apparatus  2  shown in the drawings includes a housing  4 , and a liquid-crystal panel  6  (which constitutes a display panel) and a plurality of back lights  8 , both of which are provided inside the housing  4 . The display apparatus  2  in this embodiment is a liquid-crystal television receiver which adopts the direct-backlit system and includes the back lights  8 . 
         [0042]    The housing  4  includes a front cabinet  10  and a rear frame  12  which are combined with each other. 
         [0043]    The front cabinet  10  is provided on the front side of the liquid-crystal panel  6 . The front cabinet  10  is formed into a frame shape and covers an outer-circumferential portion of the liquid-crystal panel  6 . It is to be noted that the front cabinet  10  is formed of resin or the like, for example. 
         [0044]    The liquid-crystal panel  6  is supported together with a diffuser panel (not shown) or the like by the front cabinet  10  with a cell guide (not shown) therebetween. With the rear face irradiated with light from the back lights  8  (described hereinafter), the display panel  6  displays images. 
         [0045]    The rear frame  12  is provided on the rear side of the liquid-crystal panel  6 . The rear frame  12  is slightly swollen in shape in the opposite direction from the liquid-crystal panel  6  and covers the whole rear face of the liquid-crystal panel  6 . In a central area on the outer face of the rear frame  12  (which is a face different from the face on which the back lights  8  are provided), a power source substrate (not shown) or the like for supplying electric power to the liquid-crystal panel  6 , the back lights  8 , and the like is mounted. It is to be noted that the rear frame  12  is formed of a metal having high heat conductivity, such as aluminum, for example. 
         [0046]    The rear frame  12  includes a protruding portion  14  for positioning a rear cover  16  (described hereinafter) with respect to the rear frame  12 . This protruding portion  14  extends along an outer-circumferential portion of the rear cover  16  and protrudes a little in the opposite direction from the liquid-crystal panel  6  as shown in  FIG. 3  and  FIG. 5 . 
         [0047]    To the outer face of the rear frame  12 , the rear cover  16  is joined. The above-stated power source substrate or the like is covered by this rear cover  16 . When the outer-circumferential portion of the rear cover  16  comes into contact with an inner-circumferential portion of the protruding portion  14 , the rear cover  16  is positioned with respect to the rear frame  12 . To a lower end portion of the rear cover  16 , a stand  18  for supporting the housing  4  from below is joined. It is to be noted that the rear cover  16  is formed of resin or the like, for example. 
         [0048]    As shown in  FIG. 3  and  FIG. 4 , out of the region of the rear frame  12 , a region not covered by the rear cover  16  is referred to as an outer-frame region  20  and a region covered by the rear cover  16  is referred to as an inner-frame region  22 . In other words, the outer-frame region  20  is located outside the inner-frame region  22 . As shown in  FIG. 5 , an inner face S 1  of the rear frame  12  in the outer-frame region  20  is positioned on the side of an inner face S 2  of the rear frame  12  in the inner-frame region  22  opposite the side on which the back lights  8  are positioned. To put it another way, the inner face S 1  of the rear frame  12  in the outer-frame region  20  is behind the inner face S 2  of the rear frame  12  in the inner-frame region  22  by a predetermined distance D (in the order of several millimeters (mm), for example) on the opposite side from the back lights  8 . 
         [0049]    Furthermore, the inner face of the rear frame  12  (that is, the face on which the back lights  8  are provided) is provided with a plurality of protrusions  24  for positioning a heat sink  30  (described hereinafter) with respect to the rear frame  12 . Each of the protrusions  24  protrudes a little on the liquid-crystal panel  6  side as shown in  FIG. 5 . 
         [0050]    Furthermore, the rear frame  12  is provided with a plurality of screw holes  26  for fastening with screws  40  (described hereinafter). In the rear frame  12 , a plurality of slits  28  are provided for the respective screws  40  as shown in  FIG. 6  and  FIG. 7 . Each of the slits  28  extends in an arc in part of a periphery of the screw  40  such that the arc is curved on the outer side inside the outer-frame region  20 . A function of this slit  28  is described later. 
         [0051]    The back lights  8  are supported by the inner face of the rear frame  12  as shown in  FIG. 4  so as to allow heat conduction to the inner face of the rear frame  12  (that is, to allow the heat from each of the back lights  8  to be transferred to the rear frame  12 ). When supplied with electric power from the above-stated power source substrate, each of the back lights  8  emits light toward the rear face of the liquid-crystal panel  6 . Crossing the inner-frame region  22 , each of the back lights  8  extends linearly until both end portions thereof are in the outer-frame region  20 . The back lights  8  are arranged substantially parallel to each other. 
         [0052]    Each of the back lights  8  includes the heat sink  30  and an LED bar  32  joined to the heat sink  30  as shown in  FIG. 6 . The heat sink  30  has an elongated plate shape. The LED bar  32  includes a wiring substrate  34  and a plurality of LEDs  36  (which constitute light-emitting elements) mounted on the wiring substrate  34 . The wiring substrate  34  has an elongated plate shape. The LEDs  36  are arranged at intervals in line along the longitudinal direction of the wiring substrate  34 . The wiring substrate  34  is joined to the heat sink  30  with a double sided tape  38  having heat conductivity. Each of the heat sink  30  and the wiring substrate  34  is formed of a metal having high heat conductivity, such as aluminum, for example. 
         [0053]    The heat sink  30  is fastened to the rear frame  12  with the screws  40  (which constitute connecting parts). As a feature of the display apparatus  2  in this embodiment, the screws  40  are arranged only in the inner-frame region  22  as shown in  FIG. 4 . In other words, the screws  40  are not provided in the outer-frame region  20 . Each of the screws  40  is formed of a metal, such as SUS, for example. 
         [0054]    Furthermore, the heat sink  30  includes a plurality of through holes  42  for the respective protrusions  24  stated above. As shown in  FIG. 5 , the protrusion  24  is inserted into this through hole  42 , thereby positioning the heat sink  30  on the rear frame  12 . 
         [0055]    Furthermore, as another feature of the display apparatus  2  in this embodiment, the heat sink  30  for the back lights  8  is in contact with the inner-frame region  22  of the rear frame  12 , but is not in contact with the outer-frame region  20  of the rear frame  12 , as shown in  FIG. 5 . As a result, an either end portion of the heat sink  30  and the outer-frame region  20  of the rear frame  12  have a space  44  therebetween for blocking the heat transfer from the heat sink  30  to the rear frame  12 . Such a space  44  is formed for the reason that the inner face S 1  of the rear frame  12  in the outer-frame region  20  is positioned on the side of the inner face S 2  of the rear frame  12  in the inner-frame region  22  opposite the side on which the back lights  8  are positioned as described above. 
       [Effect] 
       [0056]    Next, an effect obtained by the display apparatus  2  in this embodiment is described. When each of the LEDs  36  emits light, heat from each of the LEDs  36  is transferred to the heat sink  30  through the wiring substrate  34  and the double sided tape  38 , and heat from the heat sink  30  is transferred to the rear frame  12 . By doing so, the heat from each of the LEDs  36  is radiated through the heat sink  30  and the rear frame  12 . 
         [0057]    Generally, part of the heat from the heat sink  30  is transferred to the rear frame  12  through the screws  40 , with the result that the rear frame  12  has a relatively high temperature at each of its fastened portions with the screws  40 . In the display apparatus  2  in this embodiment, the fastened portions with the screws  40 , which will have a relatively high temperature, are located only in the inner-frame region  22  so that the temperature rise of the rear frame  12  in the outer-frame region  20  exposed to outside the display apparatus  2  can be reduced. 
         [0058]    Furthermore, the above-described space  44  blocks the heat transfer from the both end portions of the heat sink  30  to the outer-frame region  20  of the rear frame  12 . With this, the temperature rise of the rear frame  12  in the outer-frame region  20  exposed to outside the display apparatus  2  can be effectively reduced. 
         [0059]    Furthermore, the rear frame  12  includes the above-described slits  28 . If the rear frame  12  does not include the slits  28 , heat from the fastened portions with the screws  40  is transferred in the shortest path toward the outer-frame region  20  as indicated by dashed-line arrows in  FIG. 7 . Therefore, the efficiency of heat transfer from the fastened portions with the screws  40  to the outer-frame region  20  becomes relatively high, with the result that the rear frame  12  is likely to have a high temperature in the outer-frame region  20 . In contrast, when the rear frame  12  includes the above-described slits  28 , heat from the fastened portions with the screws  40  is transferred toward the outer-frame  20  in a detour path to avoid the slit  28  as indicated by solid-line arrows in  FIG. 7 . Therefore, the efficiency of heat transfer from the fastened portions with the screws  40  to the outer-frame region  20  becomes relatively low, with the result that the temperature rise of the rear frame  12  in the outer-frame region  20  can be more effectively reduced. 
         [0060]    Furthermore, since the screws  40  are not located in the outer-frame region  20 , the front end of each of the screws  40  is not seen from outside the display apparatus  2 , allowing for an improved design. 
       [Variation] 
       [0061]    Here, a variation of the slit is described with reference to  FIG. 8 .  FIG. 8  is a main-part perspective view showing the variation of the slit. The slit  28  extends in an arc in the present embodiment, but may be a slit  28 A which extends linearly as shown in  FIG. 8 . The slit  28 A is located on an outer-frame region  20 -side part of a periphery of the screw  40 . 
         [0062]    The slit  28 A includes a bent edge portion  28 Aa bent toward the liquid-crystal panel  6  (or opposite from the liquid-crystal panel  6 ). Such inclusion of the bent edge portion  28 Aa can result in the slit  28 A of a rear frame  12 A having enhanced strength. It is to be noted that the bent edge portion  28 Aa can be omitted. 
       Embodiment 2 
       [0063]    Next, a configuration of a display apparatus according to Embodiment 2 of the present invention is described with reference to  FIG. 9  and  FIG. 10 .  FIG. 9  is a plan view showing the interior of the display apparatus according to Embodiment 2 of the present invention.  FIG. 10  is a main-part sectional view of the display apparatus taken along line B-B in  FIG. 9 . 
         [0064]    As shown in  FIG. 10 , there is a heat insulating sheet  46  between the outer-frame region  20  of a rear frame  12 B and the both end portions of a heat sink  30 B in a display apparatus  2 B in this embodiment. This heat insulating sheet  46  blocks the heat transfer from the both end portions of the heat sink  30 B to the outer-frame region  20  of the rear frame  12 B. With this, the temperature rise of the rear frame  12 B in the outer-frame region  20  exposed to outside the display apparatus  2 B can be effectively reduced. 
         [0065]    Furthermore, as shown in  FIG. 9 , a transverse dimension W 1  of the heat sink  30 B in the outer-frame region  20  is larger than a transverse dimension W 2  of the heat sink  30 B in the inner-frame region  22  in a back light  8 B in this embodiment. The heat transfer from the heat sink  30 B to the rear frame  12 B is blocked in the outer-frame region  20  as described above, and when the heat sink  30 B has a large surface area in the outer-frame region  20 , the heat transferred to the heat sink  30 B can be efficiently radiated. 
         [0066]    Furthermore, as shown in  FIG. 9 , the screws  40  are arranged in a staggered pattern in the back lights  8 B in this embodiment. The rear frame  12 B will have a relatively high temperature at the fastened portion with the screw  40  as described above, and when the screws  40  are arranged in a staggered pattern, the temperature distribution in the inner-frame region  22  can be substantially uniform. 
         [0067]    Although the display apparatuses according to Embodiments 1 and 2 of the present invention have been described above, the present invention is not limited to these embodiments. For example, the above embodiments may be combined. 
         [0068]    Although the above has described the embodiments where the display apparatus is a liquid-crystal television receiver, the display apparatus may be other than the liquid-crystal television receiver, and may also be, for example, a liquid-crystal monitor for a personal computer, and the like. 
         [0069]    Although a plurality of back lights are provided in the above embodiments, it may also be possible to provide only a single back light. 
         [0070]    Although the connecting part is a screw in the above embodiments, the connecting part may be, for example, a double sided tape, a hook, a fixing claw, etc., which have heat conductivity. For example, when the connecting part is a hook provided on the heat sink, this hook is caught in a supporting hole of the rear frame. Alternatively, when the connecting part is a fixing claw provided on the rear frame, this fixing claw is inserted into a supporting hole of the heat sink and then is folded in a predetermined direction. 
         [0071]    Although the back light has a heat sink in the above embodiments, this heat sink can be omitted. In this case, the wiring substrate is supported by the rear frame via the connecting part so as to allow heat transfer therebetween. 
         [0072]    Although the whole inner face of the rear frame in the outer-frame region is positioned on the side of the inner face of the rear frame in the inner-frame region opposite a side on which the liquid-crystal panel is positioned in the above embodiments, it may be that only a portion of the whole inner face of the rear frame in the outer-frame region which corresponds to at least the back light is positioned on the side of the inner face of the rear frame in the inner-frame region opposite a side on which the liquid-crystal panel is positioned. 
         [0073]    Although the inner face of the rear frame in the outer-frame region is positioned on the side of the inner face of the rear frame in the inner-frame region opposite the side on which the liquid-crystal panel is positioned in the above embodiments, it may be that the inner face of the rear frame in the outer-frame region and the inner face of the rear frame in the inner-frame region are on the same plane and in this state, the back light in the outer-frame region is, for example, bent toward the liquid-crystal panel. With this, the back light and the outer-frame region of the rear frame can be spaced apart from each other. 
         [0074]    Alternatively, it may be that the inner face of the rear frame in the outer-frame region and the inner face of the rear frame in the inner-frame region are on the same plane and in this state, the back light is supported in the inner-frame region of the rear frame with a metallic spacer therebetween. Even with such a configuration, the back light and the outer-frame region of the rear frame can be spaced apart from each other. 
         [0075]    Although the slit extends in an arc or extends linearly in the above embodiments, the shape of the slit is not limited to these examples and may be set to another shape when needed. 
         [0076]    Although the wiring substrate is joined to the heat sink with a double sided tape in the above embodiments, the wiring substrate may be joined to the heat sink with a screw or the like, for example. 
         [0077]    Although the LED is used as an illuminant for the back light in the above embodiments, a cold cathode fluorescent lamp (CCFL) or the like can be used, for example. 
         [0078]    Although only some exemplary embodiments of the present invention have been described in detail above, those skilled in the art will readily appreciate that many modifications are possible in the exemplary embodiments without materially departing from the novel teachings and advantages of the present invention. Accordingly, all such modifications are intended to be included within the scope of the present invention. 
       INDUSTRIAL APPLICABILITY 
       [0079]    The display apparatus in the present invention is applicable, for example, as a liquid-crystal television receiver, a liquid-crystal monitor for a personal computer, and the like.