Abstract:
A liquid crystal display panel ( 39 ) includes a diffraction grating (DG) that is provided on the side of the inner surface ( 32 N) of an opposed substrate ( 32 ) for receiving light and is used for enhancing the light output efficiency from the inner surface ( 32 N) to the outside.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a display panel like, for example, a liquid crystal display panel, and a display device (e.g., a liquid crystal display device) that incorporates the display panel. 
       BACKGROUND ART 
       [0002]    In a liquid crystal display device that is able to perform color display, a color filter is incorporated in a liquid crystal display panel in many cases. And, directly under the color filter, a liquid crystal display panel, which incorporates a fluorescent body for emitting fluorescent light that has the same color as the color filter, also is present (e.g., a patent document 1). 
       CITATION LIST 
     Patent Literature 
       [0000]    
       
         PLT1: JP-A-1992-012323 
       
     
       SUMMARY OF INVENTION 
     Technical Problem 
       [0004]    A problem, which occurs in the liquid crystal display panel in which such a fluorescent body and a color filter are stacked up, is as follows. As shown in a partially enlarged view of  FIG. 11 , in the liquid crystal display panel, a fluorescent body  111 R receives blue light (backlight; bl) from a backlight unit and performs fluorescent light emission to emit red light (R). And, this light travels in various directions. For example, part (light ml) of the light from the fluorescent body  111 R travels in the inside of a red color filter  113 R and reaches an inside surface  132 N of a color filter base board  132 . 
         [0005]    In such a case, an incident angle of the light ml with respect to the inside surface  132 N (in detail, an interface between the color filter  113 R and the inside surface  132 N) exceeds a critical angle in some cases. In this case, the light ml is totally reflected by the inside surface  132 N to travel, for example, to a black matrix  114 A. 
         [0006]    The black matrix  114 A has reflectiveness rather than transmissiveness. Because of this, the light reaching the black matrix  114 A is totally reflected to travel, for example, to a band-pass filter  135  which transmits blue light but reflects red light. Because of this, the light reaching the band-pass filter  135  is reflected to travel to a black matrix  114 B. And, the light reaching the black matrix  114 B is reflected to travel to the inside surface  132 N of the color filter base board  132 . 
         [0007]    In this way, the incident angle of the light reaching the inside surface  132 N exceeds again the critical angle at the inside surface  132 N in some cases. And, such light travels to the black matrix  114 A; and further, repeating the reflection, travels to the band-pass filter  135 , the black matrix  114 B and the inside surface  132 N. 
         [0008]    In other words, of the light emitted from the fluorescent body  111 R, the light, whose incident angle to the inside surface  132 N is not smaller than the critical angle, cannot pass through the inside surface  132 N and cannot exit to outside. Because of this, in such a liquid crystal display device, the amount of light exiting from the red color filter  113 R decreases (in other words, the ratio (light output efficiency) of the amount of light exiting to outside to the amount of light emitted from the fluorescent body  111 R is relatively low). 
         [0009]    The present invention has been made to solve the above problems. And, it is an object of the present invention is to provide a display panel that improves light output efficiency; and a display device that incorporates the display panel. 
       Solution to Problem 
       [0010]    The display panel includes: a light-supply amount control portion that controls a supply amount of light; a fluorescent body that receives the light from the light-supply amount control portion and performs fluorescent light emission; and a transmission base board that transmits the light from the fluorescent body. And, in the display panel, on a light receiving surface of the transmission base board that receives the light, a light output structure, which improves output efficiency from the light receiving surface to outside, is formed. For example, the light output structure is a diffraction grating. 
         [0011]    According to this, even if an incident angle of the light with respect to the light receiving surface of the transmission base board is larger than a critical angle, the light is diffracted (diffraction transmission and diffraction reflection) by the diffraction grating without being totally reflected. In this case, the amount of light that is guided to outside via the light receiving surface increases from the amount of light that is guided to outside via a light receiving surface (light receiving surface that does not have the diffraction grating and the like) which causes the total reflection. Because of this, such a display panel is able to efficiently guide the light to outside. 
         [0012]    Here, it is desirable that a grating piece of the diffraction grating is a pillar body (e.g., a rectangular parallelepiped body or a circular cylindrical body). 
         [0013]    Besides, it is desirable that the diffraction grating includes a polygonal-shape (e.g., a triangular shape or a quadrangular shape) grating pattern. 
         [0014]    Besides, it is desirable that the grating piece of the diffraction grating is a bar-shape body whose longest edge is along a grating surface of the diffraction grating; 
         [0015]    a part of a plurality of the bar-shape bodies are arranged along a first direction that intersects with a longitudinal direction of themselves, whereby a stripe-shape first grating pattern is formed; and 
         [0016]    another part of the plurality of the bar-shape bodies are arranged along a second direction that intersects with the first direction, whereby a stripe-shape second grating pattern is formed. 
         [0017]    Besides, it is desirable that the grating piece constituting the diffraction grating is a ring-shape body; and 
         [0018]    the diffraction pattern is composed of concentric circles that are formed of a plurality of the ring-shape bodies which share a center with each other. 
         [0019]    Here, in the display panel, it is desirable that a relational expression (1) described below is met: 
         [0000]      0.5 γ≦d≦ 3γ  relational expression (1)
 
         [0020]    where
       γ: an excitation wavelength for exciting fluorescent light   d: a periodic interval of the grating piece of the diffraction grating       
 
         [0023]    Besides, in the display panel, it is desirable that a relational expression (2) described below is met: 
         [0000]      0.5 d≦H≦ 3 d   relational expression (2)
 
         [0024]    where
       d: the periodic interval of the grating piece of the diffraction grating   H: a height of the grating piece from the grating surface of the diffraction grating       
 
         [0027]    Here, it is desirable that between the diffraction grating and the fluorescent body, a color filter in accordance with a color of the light derived from the fluorescent light emission is interposed. According to this, color purity of the light traveling to outside improves. 
         [0028]    Besides, it is desirable that the fluorescent body and the color filter are enclosed by a reflective light blocking member. According to this, between the color filters having different colors, light having different colors does not travel. Because of this, the color purity of the light traveling to outside surely improves. 
         [0029]    Here, it is desirable that the reflective light blocking member is formed of a metal (e.g., aluminum or silver). 
         [0030]    Besides, the reflective light blocking member may be a band-pass filter that is able to interfere with at least a partial wavelength region of an entire region of visible light. 
         [0031]    Here, it is possible to say that a display device, which includes the above display panel; and an illumination device that supplies light to the display panel, is also the present invention. 
       Advantageous Effects of Invention 
       [0032]    According to the display panel of the present invention, even light (in short, light that is totally reflected), which impinges on the light receiving surface of the transmission base board at a relatively large incident angle, is able to pass through the light receiving surface. Because of this, such display panel is able to efficiently guide the light to outside. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0033]      FIG. 1  is a partially enlarged view of  FIG. 2 . 
           [0034]      FIG. 2  is a sectional view seen along an A-A′ line in  FIG. 10 . 
           [0035]      FIG. 3  is a plan view showing an opposite base board that includes a diffraction grating (where a grating pattern has a quadrangular shape) which is formed of a circular cylindrical grating piece. 
           [0036]      FIG. 4  is a plan view showing an opposite base board that includes a diffraction grating (where a grating pattern has a triangular shape) which is formed of a circular cylindrical grating piece. 
           [0037]      FIG. 5  is a plan view showing an opposite base hoard that includes a diffraction grating (where a grating pattern has a quadrangular shape) which is formed of a rectangular parallelepiped grating piece. 
           [0038]      FIG. 6  is a plan view showing an opposite base board that includes a diffraction grating (where a grating pattern has a triangular shape) which is formed of a rectangular parallelepiped grating piece. 
           [0039]      FIG. 7  is a plan view showing an opposite base hoard that includes a diffraction grating which is formed of a bar-shape grating piece. 
           [0040]      FIG. 8  is a plan view showing an opposite base hoard that includes a diffraction grating which is formed of grating pieces that are arranged concentrically. 
           [0041]      FIG. 9  is a light path view showing diffracted light at an opposite base board that includes a diffraction grating. 
           [0042]      FIG. 10  is an exploded perspective view of a liquid crystal display device. 
           [0043]      FIG. 11  is a light path view showing reflected light at an inside surface of an opposite base board that is incorporated in a conventional liquid crystal display device. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiment 1 
       [0044]    An embodiment is described based on drawings as follows. Here, for convenience, there is a case where a hatching, a member reference number and the like are omitted; in such a case, other drawings are referred to. Besides, a black dot in a drawing means a direction perpendicular to the paper surface. Besides, numerical examples described are only examples, and the numerical values are not limiting. 
         [0045]      FIG. 10  is an exploded perspective view showing a liquid crystal display device (display device)  69 . As shown in this figure, the liquid crystal display device  69  includes: a liquid crystal display panel (display panel)  39 ; and a backlight unit (illumination device)  49 . 
         [0046]    The liquid crystal display panel  39  attaches an active matrix base hoard  31  that includes switching elements such as a TFT (Thin Film Transistor) and the like, and an opposite base board  32  that faces the active matrix board  31  to each other by means of a seal member (not shown). And, liquid crystal  33  is injected into a gap between both base boards  31 ,  32  (see  FIG. 2  described later). Here, materials of the active matrix base board  31  and the opposite base board (transmission base board)  32  are not especially limited; for example, there is glass (the refractive index nd≈1.51). Besides, details of the liquid crystal display panel  39  are described later. 
         [0047]    The liquid crystal display panel  39  is a non-light emitting type display panel, so that the liquid crystal display panel  39  receives light (backlight BL: see  FIG. 2  described later) from the backlight unit  49 , thereby fulfilling a display function. Because of this, if the light from the backlight unit  49  is able to be evenly shined onto the entire surface of the liquid crystal display panel  39 , the display quality of the liquid crystal display panel  39  improves. Here, in the liquid crystal display device  39 , the orientation of the liquid crystal  33  is adjusted, whereby the transmittance of the liquid crystal  33  partially changes (in short, the amount of light supplied to outside changes) and a displayed image changes. Because of this, the liquid crystal (liquid crystal layer)  33  is also called a light-supply amount control portion. 
         [0048]    The backlight unit  49  includes: an LED module (light source module) MJ; a light guide plate  43 ; and a reflection sheet  44 . 
         [0049]    The LED module MJ is a module that emits light and includes: a mount base board  41 ; and an LED (Light Emitting Diode)  42  that is mounted on an electrode formed on a mount surface of the mount base board  41  and receives electricity supply to emit light. 
         [0050]    Besides, it is desirable that to secure a light amount, the LED module MJ includes a plurality of the LEDs (point light source)  42 ; further, the LEDs  42  are arranged parallelly in a line. However, in the figure, for convenience, only part of the LEDs  42  are shown (hereinafter, the arrangement direction of the LEDs  42  is also called an X direction). 
         [0051]    Besides, as the light color emitted from the LED  42 , there are various colors such as a red, a green and the like: however, the LED  42  in  FIG. 10  is a blue light emitting LED  42  that emits blue light (light whose wavelength is from about 400 nm to about 500 nm). 
         [0052]    The light guide plate  43  is a plate-shape member that has: a side surface  43 S; a top surface  43 U and a bottom surface  43 B which are so situated as to sandwich the side surface  43 S. And, a surface (light receiving surface  43 S a ) of the side surface  43 S faces a light-emitting end of the LED  42 , thereby receiving the light from the LED  42 . The received light undergoes multiple reflection in the inside of the light guide plate  43  and goes out as surface light from the top surface (output surface)  43 U to outside. 
         [0053]    Besides, hereinafter, the side surface  43 S opposite to the light receiving surface  43 S a  is defined as an opposite surface  43 S b ; and the direction from the light receiving surface  43 S a  to the opposite surface  43 S b  is called a Y direction (especially, this Y direction intersects with the X direction (e.g., intersects at right angles)). 
         [0054]    The reflection sheet  44  is so situated as to be covered by the light guide plate  43 . And, a surface of the reflection sheet  44  that faces the bottom surface  43 B of the light guide plate  43  serves as a reflection surface. Because of this, this reflection surface reflects the light from the LED  42  and the light traveling in the inside of the light guide plate  43  back into the light guide plate  43  without leaking both light (in detail, via the bottom surface  43 B of the light guide plate  43 ). 
         [0055]    Here, in the above backlight unit  49 , the reflection sheet  44  and the light guide plate  43  are stacked up in this order (here, the stack-up direction is called a Z direction; besides, it is desirable that the X direction, the Y direction and the Z direction are in a relationship to intersect with each other at right angles). And, the light from the LED  42  is changed to the surface-shape backlight BL by the light guide plate  43  and goes out; the surface light BL reaches the liquid crystal display panel  39 , whereby the liquid crystal display panel  39  displays an image. 
         [0056]    Here, the liquid crystal display panel  39  is described in detail using  FIG. 1  to  FIG. 10 .  FIG. 2  is a sectional view seen along an A-A′ line in  FIG. 10 ;  FIG. 1  is a partially enlarged view of  FIG. 2 . As shown in  FIG. 2 , the liquid crystal display panel  39 , in addition to the active matrix base board  31  and the opposite base board  32  that sandwich the liquid crystal layer  33 , includes: light polarization films  34  ( 34 P,  34 Q); a band-pass filter  35 ; a fluorescent body  11 ; a scattering body  12 ; a color filter  13 ; a black matrix  14 ; and a diffraction grating DG. 
         [0057]    The light polarization films  34  ( 34 P,  34 Q) sandwich the liquid crystal layer  33  that is sandwiched by the active matrix base board  31  and the opposite base board  32 . In other words, between the liquid crystal layer  33  and the active matrix base board  31 , one light polarization film  34 P is interposed; and between the liquid crystal layer  33  and the opposite base board  32 , the other light polarization film  34 Q is interposed. 
         [0058]    In detail, the light polarization film  34 P transmits specific polarized light of the light which passes through the active matrix base board  31 ; and guides the specific polarized light to the liquid crystal layer  33 . On the other hand, the polarization film  34 Q transmits specific polarized light of the light which passes through the liquid crystal layer  33 ; and guides the specific polarized light to the band-pass filter  35 . 
         [0059]    The band-pass filter (interference layer)  35  covers the light polarization film  34 Q. And, this band-pass filter  35  selectively transmits blue light (B) that passes through the light polarization film  34 Q; on the other hand, reflects red light (R) and green light (G) that are contained, for example, in visible light (in short, the band-pass filter  35  interferes with a partial wavelength region of the entire region of visible light). Here, the band-pass filter  35  is formed by alternately laminating SiO 2  (silicon dioxide) and TiO 2  (titanium dioxide) on a glass thin film. 
         [0060]    The fluorescent body  11  is scattered and disposed on the band-pass filter  35 . And, this fluorescent body  11  receives the light (blue light (B)) that passes through the band-pass filter  35  to emit the fluorescent light (accordingly, an excitation wavelength for exciting the fluorescent light is from about 400 nm to about 500 nm). In detail, the fluorescent body  11  is divided into two categories: one is a red fluorescent body  11 R that emits the red light (R) which has a wavelength of about 620 nm; the other is a green light-emitting body  11 G that emits the green light (G) which has a wavelength of about 550 nm. 
         [0061]    Here, the fluorescent body  11  is not especially limited; however, considering that an edge of one picture element (PIXEL) is about 30 μm or less, it is desirable that the fluorescent body  11  is formed of particles each having a particle diameter (micro-particle material) of 1 μm or less; for example, there are a nano-particle fluorescent body and an organic fluorescent body. 
         [0062]    The scattering body  12 , like the fluorescent body  11 , is scattered and disposed on the band-pass filter  35 . And, this scattering body  12 B receives the light (blue light (B)) that passes through the band-pass filter  35  to scatter the light (here, the scattering body  12  scatters the blue light (B) that passes through the band-pass filter  35 , so that the scattering body  12  is called the scattering body  12 B). 
         [0063]    Here, this scattering body  12 B, the fluorescent body  11 R and the fluorescent body  11 G are scattered on the band-pass filter  35 ; however, it is desirable that they are arranged with a specific regularity. For example, there are: a delta arrangement in which the fluorescent body  11 R, the fluorescent body  11 G and the scattering body  12 B are arranged in a triangular shape; a stripe arrangement in which the fluorescent body  11 R, the fluorescent body  11 G and the scattering body  12 B are alternately arranged in a line; and a mosaic arrangement in which the fluorescent body  11 R, the fluorescent body  11 G and the scattering body  12 B are alternately arranged in a mosaic shape. 
         [0064]    Besides, the material and shape of the scattering body  12 B are not especially limited. For example, there is a powder, which has transmissiveness to the blue light (B) and is formed of glass, a resin or the like that has a diameter of about 1 μm, as an example of the material of the scattering body  12 B. Besides, as another example, there is a thing that is obtained by roughening the surface of a material such as transparent glass (which has transmissiveness to the blue light (B)) or a resin to form a diffusion surface, which is also the scattering body  12 B. 
         [0065]    The color filter  13  separately covers the fluorescent body  11 R, the fluorescent body  11 G and the scattering body  12 B. In detail, the color filter  13 R, which transmits the red light (R), covers the fluorescent body  11 R to be interposed between the fluorescent body  11 R and the opposite base board  32 . Likewise, the color filter  13 G, which transmits the green light (G), covers the fluorescent body  11 G to be interposed between the fluorescent body  11 G and the opposite base board  32 . Besides, the color filter  13 B, which transmits the blue light (B), covers the scattering body  12 B to be interposed between the scattering body  12 B and the opposite base board  32  (here, the color filter  13  is in tight contact with the opposite base board  32 , so that the opposite base board  32  is also called a color filter base board  32 ). 
         [0066]    In other words, the color filters  13 R,  13 G and  13 B, in accordance with the colors of the light that travels from the fluorescent body  11 R, the fluorescent body  11 G and the scattering body  12 B, separately cover them. Because of this, a loss caused by the light passing through the color filter  13  is extremely small (besides, color deepness (color purity) of the light improves). Here, the material of the color filter  13  ( 13 R,  13 G and  13 B) is not especially limited. 
         [0067]    For example, there is an alkali-soluble radical polymerizable negative resist which contains an alkali-soluble polymer, a multi-functional monomer and a pigment ingredient (also inclusive of an ingredient such as a dispersant and the like necessary for pigment dispersion), which is an example of the material of the color filter  13 . In a case of the radical polymerizable negative resist that contains a styrene resin as the alkali-soluble polymer, the refractive index nd is from 1.55 to 1.60. 
         [0068]    The black matrix (light blocking member)  14  is interposed between the band-pass filter  35  and the opposite base board  32 , and separately encloses: the stacked-up fluorescent body  11 R and the color filter  13 R; the stacked-up fluorescent body  11 G and the color filter  13 G; and the stacked-up scattering body  12 B and the color filter  13 B to divide them (here, a divided region serves as a pixel). 
         [0069]    And, this black matrix  14  is formed of a metal (e.g., aluminum or silver) that has reflectiveness. Because of this, the light does not travel from one color filter  13  to another color filter  13  via an interface between the color filters  13 . In other words, the black matrix  14  secures the light blocking characteristic for every pixel (light-color mixing is prevented). 
         [0070]    The diffraction grating DG is formed on an inside surface  32 N that is a light receiving surface of the opposite base board  32  which faces the color filter  13  (e.g., the diffraction grating DG is formed by imprinting method). In detail, on the inside surface  32 N of the opposite base board  32 , grating pieces LP are densely disposed, whereby the diffraction grating DG is completed. And, the diffraction grating DG is designed based on a known RCWA method (Rigorous Coupled Wave Theory) and the following relational expression (M1). 
         [0000]        n 2·sin θ2 =n 1·sin θ1 +m·λ/d   (M1)
 
         [0000]    where 
         [0071]    n1: the refractive index of a medium (color filter  13 ) on the incident side with respect to the inside surface  32 N 
         [0072]    θ1(°): the angle (incident angle) of the light entering the inside surface  32 N with respect to the inside surface  32 N 
         [0073]    n2: the refractive index of a medium (opposite base board  32 ) on the output side with respect to the inside surface  32 N 
         [0074]    θ2(°): the angle (output angle or reflection angle) of the light refracted at the inside surface  32 N with respect to the inside surface  32 N 
         [0075]    d (nm): the periodic interval of the diffraction grating DG 
         [0076]    m: the diffraction order 
         [0077]    λ (nm): the light wavelength 
         [0000]    (here, if it is conceived that θ1, θ2 are angles that are measured in a YZ plane defined by the Y direction and the Z direction, the understanding is facilitated.) 
         [0078]    Here, the shape of the grating piece LP of such diffraction grating DG and the disposition (grating pattern of the diffraction grating DG) of the grating piece LP are not especially limited. For example, the shape of the grating piece LP of the diffraction grating DG, as shown in plan views of  FIG. 3  and  FIG. 4 , may be a cylindrical-shape pillar body (cylinder body); or, as shown in plan views of  FIG. 5  and  FIG. 6 , may be a rectangular parallelepiped pillar body (cuboid body) (here, in  FIG. 3  to  FIG. 6 , for convenience, the A-A′ line in  FIG. 10  is drawn). 
         [0079]    Besides, the disposition (grating pattern: see a one-dot-one-bar line) of the grating pieces LP, as shown in the plan views of  FIG. 3  and  FIG. 5 , may be a quadrangular shape; or, as shown in the plan views of  FIG. 4  and  FIG. 6 , may be a triangular shape (in short, the diffraction grating DG may have a polygonal-shape grating pattern.) 
         [0080]    Besides, as shown in a plan view of  FIG. 7 , the grating piece LP may be a bar-shape body whose longest edge is along the grating surface  32 N (surface formed by the grating pieces LP arranged. Here, because it is also possible to say that the grating surface is also the inside surface  32 N, the same numbers are attached) of the diffraction grating DG. And, in the case of such bar-shape grating piece LP, two kinds of diffraction patterns (first grating pattern PT 1 , second grating pattern PT 2 ) having different directions may be included in the diffraction grating DG. 
         [0081]    In detail, in the grating piece group composed of the plurality of grating pieces LP, part of the grating pieces LP are arranged along a direction (the X direction, a first direction) that intersects with a longitudinal direction of themselves (e.g., the Y direction), whereby the stripe-shape first grating pattern PT 1  is formed. Besides, another part of the grating pieces LP are arranged along a direction (the Y direction, a second direction) that intersects with the parallel-arrangement direction (the X direction) of the grating pieces LP of the first grating pattern PT 1 , whereby the stripe-shape second grating pattern PT 2  is formed. And, the first grating pattern PT 1  and the second grating pattern PT 2  are arranged neighboring each other in each of the X direction and the Y direction. 
         [0082]    Besides, as shown in a plan view of  FIG. 8 , the grating piece LP that constitutes the diffraction grating DG may be a ring-shape body. And, in the case of such ring-shape grating piece LP, as shown in  FIG. 8 , the grating pattern may be composed of concentric circles that are formed of a plurality of the ring-shape bodies which share the center with each other. 
         [0083]    And, in the cases of the grating patterns shown in  FIG. 3  to  FIG. 8 , as an example, there is the following numerical example:
       the periodic interval d of the grating piece LP of the diffraction grating DG=1000 (nm)   the height H of the grating piece LP from the grating surface  32 N of the diffraction grating DG=500 (nm)       
 
         [0086]    Here, the periodic interval d of the diffraction grating DG is designed to fall in a range of the following relational expression (1) that uses the excitation wavelength λ for exciting the fluorescent light: 
         [0000]      0.5 γ≦d≦ 3γ  relational expression (1)
 
         [0087]    Besides, the height H of the grating piece LP is designed to fall in a range of the following relational expression (2) that uses the periodic interval d (see  FIG. 1 ): 
         [0000]      0.5 d≦H≦ 3 d   relational expression (2)
 
         [0088]    Here, in the case where the above diffraction grating DG is formed on the inside surface  32 N of the opposite base board  32 , it is described using  FIG. 9  what type of behavior the light, which travels from the fluorescent bodies  11 R,  11 G and the scattering body  12 B; and passes through the color filters  13 R,  13 G and  13 B, shows. 
         [0089]    Here, for convenience, only the diffraction grating DG, which is in contact with the color filter  13 R that receives the light from the fluorescent body  11 R, is described; however, the same light behavior (the light diffracted by the diffraction grating DG) as this description also occurs in: the diffraction grating DG that is in contact with the color filter  13 G which receives the light from the fluorescent body  11 G; and the diffraction grating DG that is in contact with the color filter  13 B which receives the light from the scattering body  12 B. 
         [0090]    Besides, in  FIG. 9 , for convenience, of the black matrixes  14  that sandwich the fluorescent body  11 R and the color filter  13 R; and face each other, one is defined as a black matrix  14 A and the other is defined as a black matrix  14 B. 
         [0091]    First, as shown in  FIG. 9 , it is supposed that part (light ML) of the light from the fluorescent body  11 R travels in the inside of the color filter  13 R and reaches the inside surface  32 N (grating surface  32 N), on which the diffraction grating DG is formed, at an incident angle larger than the critical angle (see a solid-line arrow). 
         [0092]    In this case, the light ML is diffracted (diffraction transmission and diffraction reflection) with various orders by the diffraction grating DG. In other words, the diffraction grating DG is formed on the inside surface  32 N, whereby at the inside surface  32 N, the light ML having the incident angle that causes the total reflection shows a behavior other than the total reflection. 
         [0093]    For example, as the light that undergoes the diffraction transmission, there is light DP (+1) that undergoes a 1 st -order diffraction transmission. This light DP (+1) is part of the light ML, diffracted and transmitted through the grating surface  32 N; and travels to outside via the opposite base board  32  (see a broken-line arrow). 
         [0094]    Besides, as the light that undergoes the diffraction reflection, there is, for example: light DR (+1) that undergoes a 1 st -order diffraction reflection; light DR (+2) that undergoes a 2 nd -order diffraction reflection; and light DR (−1) that undergoes a −1 st -order diffraction reflection. 
         [0095]    The light DR (+1), which undergoes the 1 st -order diffraction reflection, is part of the light ML, diffracted and reflected by the grating surface  32 N; and travels to the band-pass filter  35  (see a rough one-dot-one-bar line arrow). In detail, the light DR (+1) is diffracted and reflected at a relatively small reflection angle with respect to the grating surface  32 N; and travels to the band-pass filter  35  without reaching the black matrix  14 A. And, this light DR (+1) reaches the band-pass filter  35  to be totally reflected; travels to the grating surface  32 N; and is diffracted and transmitted through the grating surface  32 N as it is. 
         [0096]    The light DR (+2), which undergoes the 2 nd -order diffraction reflection, is part of the light ML, diffracted and reflected by the grating surface  32 N; and travels to the black matrix  14 A (see a two-dot-one-bar line arrow). In detail, the light DR (+2) is diffracted and reflected at a relatively large reflection angle (a reflection angle larger than the reflection angle of the light DR (+1) with respect to the grating surface  32 N) with respect to the grating surface  32 N; and travels to the black matrix  14 A. 
         [0097]    And, the light DR (+2) is reflected by the black matrix  14 A; thereafter, travels to the band-pass filter  35 ; and is further reflected by the band-pass filter  35 . This reflected light DR (+2) travels to the black matrix  14 B; is reflected by the black matrix  14 B; travels to the grating surface  32 N; is diffracted and transmitted through the grating surface  32 N as it is (see a two-dot-one-bar line arrow). 
         [0098]    The light DR (−1) which undergoes the −1 st -order diffraction reflection is diffracted and reflected at about the same reflection angle as the incident angle of the light ML with respect to the grating surface  32 N (the diffraction reflection occurs such that the light DR (−1) returns to the original point of the travel of the light ML). And, this diffracted reflected light travels to the band-pass filter  35 ; and is further reflected by the band-pass filter  35 . This reflected light travels to the black matrix  14 B; is reflected by the black matrix  14 B; thereafter, travels to the grating surface  32 N; is diffracted and transmitted through the grating surface  32 N as it is (see a fine one-dot-one-bar line arrow). 
         [0099]    The above light (diffracted transmitted light, diffracted reflected light) diffracted by the diffraction grating DG occurs even if the light ML enters exceeding the critical angle at the inside surface  32 N. And, the diffracted transmitted light passes through the grating surface  32 N and exits to outside. Besides, the diffracted reflected light also is reflected by the band-pass filter  35  or by the band-pass filter  35  and the black matrix  14 ; returns to the grating surface  32 N to be diffracted and transmitted; and exits to outside. 
         [0100]    Because of this, if the diffraction grating DG is formed on the inside surface  32 N of the opposite base board  32  that receives the light derived from the fluorescent light emission, the amount of light exiting from the red color filter  13 R becomes relatively large (in other words, the ratio (light output efficiency) of the amount of light exiting to outside to the amount of light emitted from the fluorescent body  11 R is relatively high). For example, the light output amount from the liquid crystal display device  69  that incorporates the liquid crystal display panel  39  which includes the grating surface  32 N increases about 40 to 42% from the light output amount from the liquid crystal display device  69  that incorporates the liquid crystal display panel  39  which does no have the grating surface  32 N. 
         [0101]    Accordingly, the liquid crystal display device  69  that incorporates such liquid crystal display panel  39  is able to display an image that secures a specific brightness even if the light emission amount (light emission strength) of the LED  42  is not extremely increased. Besides, in the liquid crystal display device  69 , the light emission amount of the LED  42  is not increased, so that the power consumption of the LED  42  also is curbed so much more. 
         [0102]    Here, the diffraction grating DG, which increases the above efficiency (exit efficiency) of light output from the inside surface  32 N of the opposite base board  32  to outside, also overlaps with the fluorescent body  11 G and the color filter  13 G. And, by the diffraction grating DG that faces the color filter  13 G, like the above description, the light ML is diffracted even if the light ML impinges on the inside surface  32 N exceeding the critical angle. And, the diffracted light, like the above description, easily exits from the inside surface  32 N to outside. 
         [0103]    Besides, by the diffraction grating DG as well that overlaps with the scattering body  12 B and the color filter  13 B, like the above description, the light ML is diffracted even if the light ML impinges on the inside surface  32 N exceeding the critical angle. However, the blue diffracted reflected light (e.g., the light DR (+1), the light DR (+2), and the light DR (−1)) reaches the band-pass filter  35 . 
         [0104]    The band-pass filter  35  reflects the red light (R) and the green light (G) but transmits the blue light (B). Because of this, the blue diffracted reflected light returns to the liquid crystal layer  33  via the band-pass filter  35 . 
         [0105]    However, the amount of light that does not return to the liquid crystal layer  33  but is diffracted and transmitted through the grating surface  32 N is about the same amount of light that is derived from the fluorescent light emission from the fluorescent bodies  11 R,  11 G (in other words, in the interest of emission efficiency of the fluorescent light, the fluorescent bodies  11 R,  11 G are not able to perform the fluorescent light emission whose amount is about the same as the total amount of light from the blue LED  42 ). Because of this, the amount of light output from the respective color filters  13 R,  13 G and  13 B becomes about the same as each other. As a result of this, color unevenness of the image displayed by this liquid crystal display device  69  is unlikely to occur. 
       Other Embodiments 
       [0106]    Here, the present invention is not limited to the above embodiments, and various modifications are possible without departing from the spirit of the present invention. 
         [0107]    For example, hereinbefore, the description is performed using the liquid crystal display panel  39  which includes: the fluorescent bodies  11 R,  11 G that receive the light, which travels via the liquid crystal layer  33 , to perform the fluorescent light emission; the scattering body  12 B that receives and scatters the light that travels via the liquid crystal layer  33 ; and the opposite base board  32  that transmits the light from the fluorescent bodies  11 R,  11 G and the scattering body  12 B. And, in the liquid crystal display panel  39 , on the inside surface  32 N of the opposite base board  32  that receives the light, the diffraction grating DG, which increases the efficiency of output from the inside surface  32 N to outside, is formed. 
         [0108]    However, the diffraction grating DG may be so formed as to be able to receive the light from at least one of the fluorescent bodies  11 R,  11 G and the scattering body  12 B. In other words, the diffraction grating DG may not be formed on the entire region of the inside surface  32 N of the opposite base board  32 . For example, this is because the amount of light from the liquid crystal display panel  39  in which the diffraction grating DG is so disposed as to receive only the light from the fluorescent body  11  increases compared with the amount of light from the liquid crystal display panel  39  that does not have the diffraction grating DG at all. 
         [0109]    Besides, the diffraction grating DG is integrally formed with the inside surface  32 N of the opposite base board  32 ; however, this is not limiting, and the diffraction grating DG may be separately formed from the inside surface  32 N of the opposite base board  32  (in other words, the separate diffraction grating DG may be disposed to the inside surface  32 N of the opposite base board  32 ). In short, it is sufficient if the diffraction grating DG is situated in the path (light path) in which the light from the fluorescent body  11  or the scattering body  12 B travels to outside. 
         [0110]    Besides, the black matrix  14  is formed of the metal (aluminum, silver or the like). However, the black matrix  14  is also able to be formed of a material (e.g., a resin) other than the metal. For example, the band-pass filter may be used as the black matrix  14 . 
         [0111]    In detail, the band-pass filter  35 , which selectively reflects the light that has the same colors as the two different-color color filters  13  disposed in parallel, may be used as the black matrix  14  in the interface between the two different-color color filters  13 . For example, as the black matrix  14  that is situated in the interface between the color filter  13 R and the color filter  13 G, a band-pass filter, which transmits the blue light (B) but reflects the red light (R) and the green light (G), may be used (in short, a band-pass filter which is able to interfere with a partial wavelength region of the entire wavelength region of visible light). Of course, a band-pass filter, which is able to interfere with the entire wavelength region of visible light, may be used. 
         [0112]    According to this, without using an expensive metal material, the black matrix  14  is formed of a relatively inexpensive resin, so that it is possible to achieve cost reduction of the liquid crystal display panel  39  (and the liquid crystal display device  69 ). 
         [0113]    Besides, in the above description, as the member that controls the amount of the light (backlight) supplied from the backlight unit  49  to outside, the liquid crystal layer  33  is used. However, the member that changes the amount of the light supplied to outside is not limited to the liquid crystal layer  33 . For example, a MEMS (Micro Electro Mechanical Systems) element may be used as the member (light-supply amount control portion) that changes the amount of the light supplied to outside. 
         [0114]    Besides, the light source incorporated in the backlight unit  49  also is not limited to the blue LED  42 : an LED  42 U which emits ultraviolet rays (a wavelength of 400 nm or less) may be used. However, in a case of such LED  42 U, in the liquid crystal display device  69 , the band-pass filter  35  transmits the ultraviolet rays (UV) but reflects the light of other wavelengths. Besides, the fluorescent bodies  11 R,  11 G receive the ultraviolet rays (UV) to perform the fluorescent light emission. 
         [0115]    In other words, the fluorescent bodies  11 R,  11 G, based on the ultraviolet rays (UV), emit the red light (R) and the green light (G). Besides, instead of the scattering body  12 B shown in  FIG. 1 , a fluorescent body  11 B, which receives the ultraviolet rays (UV) to perform the fluorescent light emission, is incorporated in the liquid crystal display device  69  (here, the fluorescent body  11 B emits the blue light of a wavelength of about 470 nm). 
         [0116]    Besides, the light source incorporated in the liquid crystal display device  69  is not limited to the LED  42 , and a light source and the like, which are formed of a fluorescent lamp, a self-light emitting material such as an organic EL (Electro-Luminescence) element or an inorganic EL, may be used. Besides, in addition to the liquid crystal display panel  39 , even other display devices (e.g., a plasma display device, an organic EL display device and the like) are able to incorporate the diffraction grating DG. 
       REFERENCE SIGNS LIST 
       [0000]    
       
         
           
               11  fluorescent body 
               11 R red fluorescent body 
               11 G green fluorescent body 
               11 B blue fluorescent body 
               12 B scattering body 
               13  color filter 
               13 R red color filter 
               13 G green color filter 
               13 B blue color filter 
               14  black matrix (light blocking member) 
             DG diffraction grating (light output structure) 
             LP grating piece 
             GR 1  first grating pattern 
             GR 2  second grating pattern 
             d periodic interval of grating piece of diffraction grating 
               31  active matrix base board 
               32  opposite base board 
               32 N inside surface (light receiving surface) 
               33  liquid crystal (light-supply amount control portion) 
               34  light polarization film 
               35  band-pass filter 
               39  liquid crystal display panel (display panel) 
             MJ LED module 
               42  LED (light source) 
               43  light guide plate 
               44  reflection sheet 
               49  backlight unit 
               69  liquid crystal display device (display device)