Abstract:
Provided is an illumination device capable of preventing a reflection sheet in the periphery of a light-emitting element from being raised while minimizing the instability in the fixture of a diffusion lens. The illumination device comprises a light-emitting element, a mounting substrate, a diffusion lens, and a reflection sheet having a through-hole. The diffusing lens includes a lens portion for diffusing light, and a fixed portion to be fixed to the mounting substrate. An engaging portion that sandwiches the reflection sheet between the engaging portion and the mounting substrate is formed in the fixed portion.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an illumination device and a display device that comprises the same, more particularly, to an illumination device that includes a reflecting sheet and to a display device that comprises the same. 
       BACKGROUND ART 
       [0002]    In a liquid crystal display device (display device), a display panel is of non light emitting type; accordingly, usually, a backlight device (illumination device), which shines light onto the display panel, is incorporated. As such a backlight device, a backlight device of direct type is known, which comprises a plurality of LEDs (light emitting element) and a reflecting sheet that reflects light emitted from the LED to a display panel. 
         [0003]      FIG. 7  is a cross-sectional view showing schematically a structural example of a conventional display device that comprises a backlight device of direct type that includes a plurality of LEDs and a reflecting sheet.  FIG. 8  and  FIG. 9  are each a cross-sectional view showing a structure around the LED of the conventional display device shown in  FIG. 7 . As shown in  FIG. 7 , a display device  1001  comprises a liquid crystal display panel  1002  and a backlight device  1010  that shines light onto the liquid crystal display panel  1002 . The backlight device  1010  includes: a plurality of LEDs  1011 ; a mounting, board  1012  on which the plurality of LEDs  1011  are mounted: a plurality of diffusing lenses  1013  that diffuse light emitted from the LEDs  1011 ; a reflecting sheet  1014  that reflects light emitted from the LEDs  1011  to the liquid crystal display panel  1002  side; a diffusing plate  1015  and a plurality of optical sheets  1016  that are disposed in front (the liquid crystal display panel  1002  side) of the diffusing lens  1013 ; and a chassis  1017  that houses the LEDs  1011 , the mounting board  1012  and the like. 
         [0004]    As shown in  FIG. 8 , the diffusing lens  1013  is fixed to the mounting board  1012  to cover the LED  1011 . The reflecting sheet  1014  is provided with a through-hole  1014   a  through which the diffusing lens  1013  is disposed, and disposed on the mounting board  1012 . Besides, the reflecting sheet  1014  is fixed to the mounting board  1012  by means of a rivet  1020  or a not-shown adhesive layer (double-coated tape or the like). 
         [0005]    In the case of using the rivet  1020 , the rivet  1020  is often disposed at a position far from the LED  1011  not to block the illumination light. Because of this, as shown in  FIG. 9 , there is a case where the reflecting sheet  1014  is raised around the mounting board  1012 . In this case, there is a disadvantage that part of the light emitted from the LED  1011  goes under the reflecting sheet  1014 ; whereby brightness unevenness easily occurs and light loss occurs. 
         [0006]    To improve the above disadvantage, illumination devices are proposed, which alleviate the rising, of a reflecting sheet by means of a diffusing lens (e.g., patent documents 1 and 2). 
         [0007]    The patent document 1 discloses a light source device (illumination device) that has a plurality of light emitting diodes (light emitting elements); a light emitting diode board (mounting board) on which the plurality of light emitting diodes are mounted; a diffusing lens that diffuses the light emitted from the light emitting diode; and a reflecting sheet that is provided with a through-hole, through which the diffusing lens is disposed, and disposed on the light emitting diode board. 
         [0008]    The diffusing lens includes a lens portion that diffuses the light emitted from the light emitting diode and a positioning protrusion (fixing portion) that protrudes from the lens portion to the light emitting diode board to be fixed to the light emitting diode board. The lens portion is provided with a convex portion that protrudes in parallel with a surface of the light emitting diode board. The convex portion cooperates with the light emitting diode board to sandwich the reflecting sheet, thereby alleviating the rising of the reflecting sheet. 
         [0009]    The light source device in the patent document 1 alleviates the rising of the reflecting sheet by means of the diffusing lens; accordingly, it is possible to somewhat alleviate the reflecting sheet being raised from the light emitting diode board around the light emitting diode. Because of this, it is possible to somewhat alleviate the light emitted from the light emitting diode going under the reflecting sheet, and it is possible to somewhat alleviate the brightness unevenness and light loss. 
         [0010]    The patent document 2 discloses a light emitting device (illumination device) that comprises: a plurality of light emitting elements; a board (mounting board) on which the plurality of light emitting elements are mounted; a luminous flux control member (diffusing lens) that diffuses the light emitted from the light emitting element; and a reflecting sheet disposed on the board. 
         [0011]    The luminous flux control member includes: a lens portion that diffuses the light emitted from the light emitting element; and three supporting, legs that protrude from the lens portion toward the board. Two supporting legs are fixed to the board. The one remaining supporting leg is formed shorter than the two supporting legs and disposed on the reflecting sheet. The one supporting leg cooperates with the board to sandwich the reflecting sheet, thereby alleviating the rising of the reflecting sheet. 
       CITATION LIST 
     Patent Literature 
       [0012]    PLT1: JP-A-2011-3535 
         [0013]    PLT2: JP-A-2011-86569 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0014]    However, in the patent document 1, the convex portion for alleviating the rising of the reflecting sheet is formed on the lens portion of the diffusing lens; accordingly, the distance from the light emitting diode board to the portion (convex portion) for alleviating the rising of the reflecting sheet becomes long. Because oil this the gap between the reflecting sheet and the portion (convex portion) for alleviating the rising of the reflecting sheet becomes large; accordingly, there is a problem that it is hard to sufficiently alleviate the rising of the reflecting sheet. 
         [0015]    The light emitting device in the patent document 2 alleviates the rising of the reflecting sheet by means of the supporting leg of the luminous flux control member. Because of this, compared to the case (case of the patent document 1) where the rising of the reflecting sheet is alleviated by means of the lens portion, it is possible to shorten the distance from the board to the portion (one supporting leg) for alleviating the rising of the reflecting sheet. According to this, it is possible to make small the gap between the reflecting sheet and the portion (one supporting leg) for alleviating the rising of the reflecting sheet. Because of this, it is possible to more alleviate the reflecting sheet being raised from the board around the light emitting element. In this way, it is possible to more alleviate the light emitted from the light emitting element going under the reflecting sheet, and possible to more alleviate the brightness unevenness and light loss. 
         [0016]    However, in the patent document 2, the one supporting leg is not fixed to the board; accordingly, there is a problem that the fixing of the diffusing lens becomes unstable. Besides, in the patent document 2, it is necessary to fix the diffusing lens after the reflecting sheet is disposed on the board. Because of this, it is necessary to fix the reflecting sheet to the board by means of an adhesive layer or the like until the diffusing lens is fixed; accordingly, the production process becomes onerous. Besides, for example, in a case where the mounting board is repaired, it is necessary to demount all the diffusing lenses before demounting the reflecting sheet; accordingly, it is hard to repair the mounting board and the like. 
         [0017]    The present invention has been made to solve the above problems, and it is an object of the present invention to provide: an illumination device that is able to alleviate the rising of a reflecting sheet around a light emitting element while alleviating the fixing of a diffusing lens becoming unstable; and a display device that comprises the illumination device. 
       Solution to Problem 
       [0018]    To achieve the object, an illumination device comprising: a light emitting element, a mounting board on which the light emitting element is mounted, a diffusing lens that is disposed to cover a light emitting side of the light emitting element and diffuse light emitted from the light emitting element, and a reflecting sheet  t hat is provided with a through-hole, through which the diffusing lens is disposed, and disposed on the mounting board, wherein the diffusing, lens includes: a lens portion that diffuses the light emitted from the light emitting element; and a fixing portion that protrudes from the lens portion to the mounting board side and is fixed to the mounting board, and the fixing portion is provided with an engaging portion that cooperates with the mounting board to sandwich the reflecting sheet. 
         [0019]    In this illumination device, as described above, the diffusing lens includes the lens portion and the fixing portion, and the fixing portion is provided with the engaging portion that cooperates with the mounting hoard to sandwich the reflecting sheet. In other words, the diffusing lens alleviates the rising of the reflecting sheet. In this way, it is possible to alleviate the reflecting sheet being raised from the mounting board around the light emitting element. Besides, the raising of the reflecting sheet is alleviated by means of the engaging portion formed on the fixing portion of the diffusing lens; accordingly, compared to the case where the rising of the reflecting Sheet is alleviated by means of the lens portion of the diffusing lens, it is possible to shorten the distance from the mounting board to the portion (engaging portion of the fixing portion) that alleviates the rising of the reflecting sheet. In this way, it is possible to make small the gap between the reflecting sheet and the portion (engaging portion of the fixing portion) that alleviates the rising of the reflecting sheet. Because of this, it is possible to sufficiently alleviate the reflecting sheet being raised from the mounting board around the light emitting element. As a result of this, it is possible to sufficiently alleviate the light emitted from the light emitting element going under the reflecting sheet; accordingly, it is possible to sufficiently alleviate the brightness unevenness and light loss. 
         [0020]    Besides, as described above, the fixing portion fixed to the mounting board is provided with the engaging portion that alleviates the rising of the reflecting sheet, In this way, it is possible to alleviate the rising of the reflecting sheet while preventing the fixing of the diffusing lens from becoming unstable. 
         [0021]    Besides, as described above, the reflecting sheet is provided with the through-hole through which the reflecting lens is disposed, and the fixing portion is provided with the engaging portion that cooperates with the mounting board to sandwich the reflecting sheet. In this way, after the diffusing lens is fixed to the mounting board, it is possible to dispose the reflecting sheet onto the mounting board and engage the reflecting sheet with the engaging portion. Because of this, it is unnecessary to fix the reflecting sheet to the mounting board by means of an adhesive layer or the like; accordingly, it is possible to alleviate the production process becoming onerous. Besides, for example, in a case of repairing the mounting board, it is possible to demount the reflecting sheet without demounting the diffusing lens; accordingly, it is possible to easily perform the repairing of the mounting board and the like. 
         [0022]    In the above illumination device, preferably, the engaging portion is formed into a concave shape. According to such a structure, it is possible to alleviate the through-hole of the reflecting sheet becoming large; accordingly, it is possible to alleviate the light loss increasing. In the meantime, in the case where the diffusing lens is provided with a convex portion that protrudes in parallel with a surface of the mounting board as in the patent document 1, it is necessary to form the through-hole of the reflecting sheet large; accordingly, the light loss increases. 
         [0023]    In the above illumination device, preferably, the engaging portion includes: a first engaging surface that engages with an inner surface of the through-hole of the reflecting sheet; and a second engaging surface that engages with a surface of the reflecting sheet opposite to a surface that faces the mounting board. According to such a structure, it is possible to limit movement of the reflecting sheet in a surface direction (direction parallel to the surface) and movement (rising of the reflecting sheet) of the reflecting sheet in a thickness direction by means of the engaging portion. 
         [0024]    In the above illumination device, preferably, a plurality of the diffusing lenses are disposed, and each of the diffusing lenses is provided with the engaging portion at a portion on the same side. According to such a structure, it is possible to easily engage the reflecting sheet with each engaging portion by disposing the reflecting sheet onto the mounting board and sliding the reflecting sheet in a predetermined direction (opposite to the side where the engaging portion is formed). 
         [0025]    In this case, preferably, the diffusing lens includes a plurality of the fixing portions, and the engaging portion is formed on all the fixing portions. According to such a structure, when fixing the diffusing lens onto the mounting board, it becomes unnecessary to align the directions (mounting directions) of the diffusing lenses; accordingly, it is possible to improve the mounting work of the diffusing lenses. 
         [0026]    A display device according to this invention comprises: the illumination device having the above structure, and a display panel that uses light from the illumination device to perform display. According to such a structure, it is possible to obtain a display device that is able to alleviate the rising of the reflecting, sheet around the light emitting element while alleviating the fixing of the diffusing lens becoming unstable. 
       Advantageous Effects of Invention 
       [0027]    As described above, according to the present invention, it is possible to obtain: an illumination device that is able to alleviate the rising of a reflecting sheet around a light emitting element while alleviating the fixing of a diffusing lens becoming unstable; and a display device that includes the illumination device. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0028]      FIG. 1  is a cross-sectional view showing schematically a structure of a display device that comprises an illumination device according to a first embodiment of the present invention. 
           [0029]      FIG. 2  is a cross-sectional view showing a structure around a diffusing lens of the illumination device shown in  FIG. 1  according to the first embodiment of the present invention. 
           [0030]      FIG. 3  is an enlarged cross-sectional view showing structures of a diffusing lens and a light emitting element of the diffusing device shown in  FIG. 1  according to the first embodiment of the present invention. 
           [0031]      FIG. 4  is a cross-sectional view showing a state in which a reflecting sheet of the illumination device shown in  FIG. 1  according to the first embodiment of the present invention is disposed on a mounting board. 
           [0032]      FIG. 5  is a cross-sectional view showing a state in which a reflecting sheet of the illumination device shown in  FIG. 1  according to the first embodiment of the present invention is slid. 
           [0033]      FIG. 6  is an enlarged cross-sectional view showing a structure of a diffusing lens according to a second embodiment of the present invention. 
           [0034]      FIG. 7  is a cross-sectional view showing schematically a structural example of a conventional display device that comprises a backlight device of direct type which includes a plurality of LEDs and a reflecting sheet. 
           [0035]      FIG. 8  is a cross-sectional view showing a structure around a diffusing lens of the conventional display device shown in  FIG. 7 . 
           [0036]      FIG. 9  is a cross-sectional view showing a structure around a diffusing lens of the conventional display device shown in  FIG. 7 . 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0037]    Hereinafter, embodiments of the present invention are described with reference to the drawings. In the meantime, there is a case where hatching is not applied, even to a cross-sectional view for the sake of easy understanding, 
       First Embodiment 
       [0038]    With reference to  FIG. 1  to  FIG. 5 , a structure of a display device  1 , which comprises an illumination device  10  according to an first embodiment of the present invention, is described. The display device  1  according to the first embodiment of the present invention is used for a television receiver and the like, for example, Besides, as shown in  FIG. 1 , the display device  1  comprises a display panel  2 , and the illumination device  10  that is disposed near a rear side of the display panel  2  and illuminates the display panel  2 . 
         [0039]    The display panel  2  includes a liquid crystal display panel, and has two glass boards that sandwich a liquid crystal layer which is not shown. Besides, the display panel  2  uses light from the illumination device  10  to display an image. 
         [0040]    The illumination device  10  is a backlight device of direct type. Besides, the illumination device  10  includes; a plurality of light emitting elements  11 ; a mounting board  12  on which the plurality of light emitting elements  11  are mounted; a plurality of diffusing lenses  13  that are disposed to cover a light emitting side (side facing the display panel  2 ) of the light emitting element  11 ; a reflecting sheet  14  disposed on the mounting board  12 ; a diffusing plate  15  that is disposed to cover the light emitting element  11  and the diffusing lens  13 ; a plurality of optical sheets  16  disposed on a front surface (surface facing the display panel  2 ) of the diffusing plate  15 ; and a chassis  17  that houses the light emitting elements ii and the mounting board  12 . 
         [0041]    The plurality of light emitting elements  11  are disposed into a matrix shape. The light emitting element  11  is composed of an LED, for example, and emits white light. 
         [0042]    As shown in  FIG. 2 , the reflecting sheet  14  is provided with a through-hole  14   a  through which the diffusing lens  13  is disposed. The reflecting sheet  14  has a function to reflect light emitted from the light emitting element to the display panel  2  side. 
         [0043]    The diffusing lens  13  is formed of a material (e.g., resin or glass) that transmits light and has a function to diffuse and transmit the light from the light emitting element  11  to the display panel  2  side. The diffusing lens  13  is disposed to cover the light emitting element  11  and formed one for one light emitting element  11 . The diffusing lens  13  is fixed to a predetermined position of the mounting hoard  12 . 
         [0044]    As shown in  FIG. 3 , the diffusing lens  13  includes: a lens portion  13   a  that diffuses the light emitted from the light emitting element  11 ; and a plurality of (e.g., three) fixing portions  13   b  that protrude from the lens portion  13   a  toward the mounting board  12 . The lens portion  13   a  includes a concave-shaped light entering surface  13   c  from which the light emitted from the light emitting element  11  enters; and a light output surface  13   d  that outputs the light. In the meantime, the drawing illustrates an example in which the light output surface  13   d  is formed into substantially a hemisphere-shaped surface; however, the light output surface  13   d  may be formed into another shape that is a combination of for example, a convex shape and a concave shape. 
         [0045]    The fixing portion  13   b  is formed into, for example, a cylindrical shape and formed not to extend beyond a contour of the lens portion  13   a  when viewed from top. The fixing portions  13   b  are farmed on the diffusing lens  13  by three, for example, and disposed at an angle interval of 120° around a center of the lens portion  13   a.    
         [0046]    The fixing portion  13   b  is fixed to the mounting board  12  by means of an. adhesive layer (not shown), for example. In the present embodiment, as to each diffusing lens  13 , one of the plurality of (e.g., three) fixing portions  13   b  is provided with one concave-shaped engaging portion  13   e.  The engaging portion  13   e  includes: an engaging surface  13   f  (first engaging surface) that engages with an inner surface of the through-hole  14   a  of the reflecting sheet  14 ; and an engaging surface  13   g  (second engaging surface) that engages with a front surface (surface opposite to a surface that faces the mounting board  12 ) of the reflecting sheet  14 . In this way, the engaging portion  13   e  cooperates with the mounting, board  12  to sandwich the reflecting sheet  14 , and engages with the through-hole  14   a  of the reflecting sheet  14 . 
         [0047]    Besides, as shown in  FIG. 2 , in a state in which the plurality of diffusing lenses  13  are fixed to the mounting board  12 , each of the engaging portions  13   e  is formed at a portion (right portion in the drawing) on the same side of the diffusing lens  13 . In an assembly process of the illumination device  10 , after the light emitting element  11  is mounted onto the mounting hoard  12 , the diffusing lens  13  is fixed to the mounting board  12 . At this time, the directions (mounting directions) of the diffusing lenses  13  are aligned such that each engaging portion  13   e  faces the same direction (right side in the drawing). And, as shown in  FIG. 4 , the reflecting sheet  14  is disposed onto the mounting board  12 . Thereafter, the reflecting sheet  14  is slid in a direction (left side in the drawing) opposite to the same side, whereby as shown in  FIG. 5 , the through-hole  14   a  of the reflecting sheet  14  engages with the engaging portion  13   e  of the diffusing lens  13 . In this way, movement in the direction opposite (left side in the drawing) to the same side of the reflecting sheet  14  and movement (rising of the reflecting sheet  14 ) of the reflecting sheet  14  toward the display panel  2  are limited. 
         [0048]    As shown in  FIG. 1 , the diffusing plate  15  includes a resin plate-shaped member, and closes an opening of the chassis  17  that faces the display panel Besides, the diffusing plate  15  has a function to diffuse the light from the diffusing lens  13  and transmit the light to the display panel  12 . A rear surface of the diffusing plate  15  may be supported by a plurality of supporting pins (not shown). The supporting pin may be fixed to the chassis  17 , for example. The reflecting sheet  14  may be provided with an insertion hole (not shown) for inserting the supporting pin. 
         [0049]    The plurality of optical sheets  16  include a resin sheet-shaped member thinner than the diffusing plate  15  and are disposed on the side of the diffusing plate  15  that faces the display panel  2 . The optical sheets  16  perform diffusion and collection of the light transmitted through the diffusing plate  15 , in the meantime, the kind of the optical sheets  16  utilized is changeable in accordance with uses. 
         [0050]    In the present embodiment, as described above, the diffusing plate  13  is provided with the engaging portion  13   e  that cooperates with the mounting board  12  to sandwich the reflecting sheet  14 . In other words, the rising of the reflecting sheet  14  is alleviated by means of the engaging portion  13   e  formed on the diffusing lens  13 ; accordingly, it is possible to alleviate the reflecting sheet  14  being raised from the mounting board  12  around the light emitting element  11 . Besides, the rising of the reflecting sheet  14  is alleviated by means of the engaging portion  13   e  formed on the fixing portion  13   b  of the diffusing lens  13 ; accordingly, compared to the case where the rising of the reflecting sheet  14  is alleviated by means of the lens portion  13   a  of the diffusing lens  13 , it is possible to shorten the distance from the mounting hoard  12  to the portion (engaging surface  13   g  of the fixing portion  13   b ) that alleviates the rising of the reflecting sheet  14 . In this way, it is possible to sufficiently make small the gap between the reflecting sheet  14  and the portion (engaging surface  13   g  of the fixing portion  13   b ) that alleviates the rising of the reflecting sheet  14 . Because of this, it is possible to sufficiently alleviate the reflecting sheet  14  being raised from the mounting board  17  around the light emitting element  11 . As a result of this, it is possible to sufficiently alleviate the light emitted from the light emitting element  11  going under the reflecting sheet  14 ; accordingly, it is possible to sufficiently alleviate the brightness unevenness and light loss. 
         [0051]    Besides, as described above, by forming the engaging portion  13   e,  which alleviates the rising of the reflecting sheet  14 , on the fixing portion  13   b  fixed to the mounting board  12 , it is possible to alleviate the rising of the reflecting sheet  14  while preventing the fixing of the diffusing lens  13  from becoming unstable. 
         [0052]    Besides, as described above, the reflecting sheet  14  is provided with the through-hole  14   a  through which the diffusing lens  13  is disposed, and the fixing portion  13   b  is provided with the engaging portion  13   e  that cooperates with the mounting board  12  to sandwich the reflecting sheet  14 . In this way, after the diffusing lens  13  is fixed to the mounting board  12 , it is possible to dispose the reflecting sheet  14  onto the mounting board  12  and engage the reflecting sheet  14  with the engaging portion  13   e.  Because of this, it is unnecessary to fix the reflecting sheet  14  to the mounting hoard  12  by means of an adhesive layer and the like; accordingly, it is possible to alleviate the production process becoming onerous. Besides, for example, in a case of repairing the mounting hoard  12 , it is possible to demount the reflecting sheet  14  without demounting the diffusing lens  13 ; accordingly, it is possible to easily perform the repairing of the mounting board  12  and the like. 
         [0053]    Besides, as described above, the engaging portion  13   e  is formed into the concave shape. In this way, it is possible to alleviate the through-hole  14   a  of the reflecting sheet  14  becoming huge; accordingly, it is possible to alleviate the light loss increasing. in the meantime, as in the patent document 1, in a case where the diffusing lens is provided with a convex portion that protrudes in parallel with a surface of the mounting board, it is necessary to form the through-hole of the reflecting sheet large: accordingly, the light loss increases. 
         [0054]    Besides, as described above, the engaging portion  13   e  includes: the engaging surface  13   f  that engages with the inner surface of the through-hole  14   a  of the reflecting sheet  14  and the engaging surface  13   g  that engages with the front surface (surface opposite to the surface that faces the mounting board  12 ). In this way, it is possible to limit, by means of the engaging portion  13   e,  movement of the reflecting sheet  14  in a surface direction and (direction parallel, to the surface) and movement (rising of the reflecting sheet  14 ) of the reflecting sheet  14  in a thickness direction. 
         [0055]    Besides, as described above, the plurality of diffusing lenses  13  are formed, and each of them is provided with the engaging portion  13   e  at the portion on the same side. In this way, by disposing the reflecting sheet  14  onto the mounting board  12  and sliding the reflecting sheet  14  in the direction (direction opposite to the side where the engaging portion  13   e  is formed) opposite to the same side, it is possible to easily engage the reflecting sheet  14  with each engaging portion  13   e.    
       Second Embodiment 
       [0056]    As shown in  FIG. 6 , in a second embodiment of the present invention, the diffusing lens  13  includes a plurality of (e.g., three) fixing portions  13   b,  and the engaging portion  13   e  is formed on the outer portions (opposite portion with respect to the center of the lens portion  13   a ) of all the fixing portions  13   b.    
         [0057]    The other structures of the second embodiment are the same as the above first embodiment. 
         [0058]    In the present embodiment, as described above, the engaging portion  13   e  is formed on all the fixing portions  13   b.  In this way, when fixing the diffusing lenses  13  to the mounting, board  12 , it becomes unnecessary to align the directions (mounting directions) of the diffusing lenses  13 ; accordingly, it is possible to improve the mounting work of the diffusing lenses  13 . 
         [0059]    The other effects of the second embodiment are the same as the above first embodiment. 
         [0060]    In the meantime, it should he considered that the embodiments disclosed this time are examples in all respects and are not limiting. The scope of the present invention is not indicated by the above description of the embodiments but by the claims, and all modifications within the scope of the claims and the meaning equivalent to the claims are covered. 
         [0061]    For example, in the above embodiments, the example, in which the display panel is applied to the liquid crystal display panel, is described; however, the present invention is not limited to this, but may be applied to a display panel other than the liquid crystal display panel. 
         [0062]    Besides, in the above embodiments, the backlight device, which illuminates the display panel as an example of the illumination device, is described; however, the present invention is not limited to this, but is also applicable to an illumination device that illuminates a member to be illuminated other than the display panel. For example, the present invention is also applicable to a ceiling illumination device that comprises a panel (member to be illuminated), an illumination device that illuminates a display board (member to be illuminated) of a sign from a rear side and the like. 
         [0063]    Besides, in the above embodiments, the example, in which the light emitting element is structured to emit the while light, is described; however, the present invention is not limited to this, but the light emitting element may be structured to emit light other than the white light. 
         [0064]    Besides, in the above embodiments the example, in which the engaging portion is formed into the concave shape, is described; however, the present invention is not limited to this, but the engaging portion may be formed into a convex shape. 
       REFERENCE SIGNS LIST 
       [0065]      1  display device 
         [0066]      2  display panel 
         [0067]      10  illumination device 
         [0068]      11  light emitting element 
         [0069]      12  mounting hoard 
         [0070]      13  diffusing lens 
         [0071]      13   a  lens portion 
         [0072]      13   b  fixing portion 
         [0073]      13   e  engaging portion 
         [0074]      13   f  engaging surface (first engaging surface) 
         [0075]      13   g  engaging surface (second engaging surface) 
         [0076]      14  reflecting sheet 
         [0077]      14   a  through-hole