Abstract:
Provided is an illumination device in which it is possible to suppress a member mounted with a light source such as an LED from being displaced, and to make said member and the illumination device smaller. A backlight unit ( 49 ) is provided with a plurality of mounting substrates ( 11 ) having various shapes, wherein the shapes are formed in a manner such that if at least one mounting substrate ( 11 ) were to move in either of two intersecting directions in the plane of the substrate, the two neighboring mounting substrates would be shaped so as to come into contact with and restrict one of the other neighboring mounting substrates ( 11 ).

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an illumination device that supplies light to a display panel which is used for a television set, a digital signage or the like, and to a display device that includes the illumination device and the display panel. 
       BACKGROUND ART 
       [0002]    In a liquid crystal display device (display device) that incorporates a liquid crystal display panel (display panel) of non-light emitting type, usually, a backlight unit (illumination device) for supplying light to the liquid crystal display panel also is incorporated. There are various kinds of light sources in a backlight unit. For example, in case of a backlight unit disclosed in a patent document 1, the light source is an LED (Light Emitting Diode). 
         [0003]    In the backlight unit described in this patent document 1, as shown in a sectional view of  FIG. 7A , an area light emitting source  181  houses an LED  121 . And, a circumference of this area light emitting source  181 , as shown in a plane view of  FIG. 7B , is provided with a concave portion  182 A and a convex portion  182 B. Because of this, in case where the area light emitting sources  181  neighbor each other, the concave portion  182 A and the convex portion  182 B fit in each other, whereby each area light emitting source  181  is unlikely to deviate. 
       CITATION LIST 
     Patent Literature 
       [0004]    PLT1: JP-A-2009-176899 
       SUMMARY OF INVENTION 
     Technical Problem 
       [0005]    However, in the backlight unit  149  described in the patent document 1, thanks to the concave portion  182 A and the convex portion  182 B formed on the circumference of the area light emitting source  181 , the area light emitting source  181  becomes large. As a result of this, also the backlight unit  149  incorporating a plurality of the area light emitting sources  181  becomes large. 
         [0006]    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 alleviates deviation of a member (e.g., a mount board for mounting an LED) on which a light source such as an LED or the like is mounted, makes the member small to achieve size reduction. 
       Solution to Problem 
       [0007]    The illumination device includes a light source and a plurality of mount boards on which the light source is mounted. And, in this illumination device, the plurality of mount boards are disposed so as to be in tight contact with one another; a shape of the mount board is a polyomino; at least one kind of the shape includes a portion of a circumference of the mount board that defines an L-shaped portion which encloses a neighboring mount board. 
         [0008]    The polyomino is a polygon formed by connecting edges of a plurality of squares to one another. And, there are a plurality of kinds of polygons; when at least one kind of polygon includes a circumference of the mount board that defines an L-shaped portion which encloses a neighboring mount board, the mount board including the L-shaped portion is situated so as to fit another mount board in the L-shaped portion. Accordingly, of the neighboring mount boards, even if a try is performed to move one mount board to the L-shaped portion, the one mount board comes into contact with the other mount board that includes the L-shaped portion and does not move. As a result of this, in this illumination device, although a plurality of the mount boards are incorporated, each mount board is unlikely to deviate. 
         [0009]    In addition, a shape is formed, with which neighboring mount boards restrict each other as a whole; accordingly, the circumference of the mount board does not need a dedicated engagement portion (e.g., a concave portion and a convex portion that mesh with each other). Because of this, the mount board becomes the smaller because the mount board does not have the dedicated engagement portion. 
         [0010]    Here, it is desirable that the plurality of mount boards disposed so as to be in tight contact with each other include: mount boards having an identical kind of shape and mount boards having different kinds of shapes mingled with each other; only mount boards having the different kinds of shapes; or mount boards having the identical kind of shape. In short, if the neighboring mount boards are in tight contact with each other as if they grip each other, the kind of shape of the mount board is not especially limited. 
         [0011]    For example, as the kind of shape of the mount board, there may be seven kinds of shapes that include: an I shape; a first L shape that is an L shape; a second L shape obtained by turning over the first L shape; a first step shape that is a step shape; a second step shape obtained by turning over the first step shape; a T shape; and a quadrangular shape. 
         [0012]    Here, the mount boards having various shapes are each an aggregate of a plurality of mount board pieces; and as a kind of shape of the mount board piece, there may be a single kind of shape or a plurality of kinds of shapes. In short, if the mount board has a predetermined shape, the kind of shape of the mount board piece included is not especially limited. 
         [0013]    Besides, it is desirable that every one of the mount boards includes the mount board pieces to the number of four as a whole; and at least one light source is disposed on every one of the mount board pieces. A reason is that according to this, many kinds of light sources are included in the mount board and it becomes possible to suitably change a distribution density of the light sources. 
         [0014]    Here, it is desirable that a connector, which includes a positive terminal electrically connected to a positive electrode of the light source and a negative terminal electrically connected to a negative electrode of the light source, is mounted on a circumference of the mount boards having the various shapes; and the terminals having identical electrodes of the connectors of neighboring mount boards are electrically connected to each other. Especially, in case where every one of the mount boards is an aggregate of four mount board pieces having shapes identical to one another; and on every one of the mount board pieces, the light source is mounted, it is desirable that the connector is mounted on every circumference of the mount board pieces corresponding to the circumference of the mount board. A reason is that according to this, no matter how the mount boards neighbor one another so as to be in tight contact with one another, the connectors of the mount boards are electrically connected to one another. 
         [0015]    Besides, as an example of the light source, there is a light emitting element. Here, a plurality of the light emitting elements may include a red light emitting element, a green light emitting element, and a blue light emitting element mingled with one another, or may be white light emitting elements. 
         [0016]    Here, it is desirable that the illumination device includes a power adjustment portion that adjusts an amount of power supplied to the light source. 
         [0017]    Besides, it is desirable that the illumination device includes a diffusion member that diffuses light from the light source, and it is desirable that the illumination device includes a brightness improvement member that transmits the light from the light source to improve brightness. 
         [0018]    Besides, it is sayable that a display device, which includes the illumination device and a display panel (e.g., a liquid crystal display panel) that receives the light from the illumination device, is also the present invention. 
       Advantageous Effects of Invention 
       [0019]    According to the present invention, in an illumination device, even if a plurality of mount boards are disposed, these mount boards are unlikely to deviate and the plurality of mount boards become small as a whole. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0020]    [ FIG. 1 ] is a plan view showing a mount board of a backlight unit. 
           [0021]    [ FIG. 2 ](A) to (G) are each a plan view showing a shape of a mount board. 
           [0022]    [ FIG. 3 ] is an enlarged plan view of a mount board piece. 
           [0023]    [ FIG. 4 ] (A) and (B) are each a plan view showing a disposition example of a mount board. 
           [0024]    [ FIG. 5 ] is a perspective view showing a display device that is used for a digital signage. 
           [0025]    [ FIG. 6 ] is an exploded perspective view (schematic view) in case where a display device is a liquid crystal display device. 
           [0026]    [ FIG. 7 ](A) is a sectional view of an area light emitting source that includes an LED contained in a conventional backlight unit; (B) is a plan view showing a plurality of area light emitting sources that are arranged in parallel with one another. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0027]    An embodiment is described based on drawings as follows. Here, for the sake of convenience, there is case where member numbers and the like are omitted; in such a case, other drawings are referred to. 
         [0028]      FIG. 5  is a perspective view showing an example of a digital signage. In detail, as shown in  FIG. 5 , a display device  69  mounted on a building BG that faces a road RD or the display device  69  disposed in front of the building BG plays a role of a digital signage. 
         [0029]    In case where the display device  69  is, for example, a liquid crystal display device, as shown in a schematic view of  FIG. 6 , the display device  69  includes a liquid crystal display panel (display panel)  59  and a backlight unit (illumination device)  49  that supplies light to the liquid crystal display panel  59 . 
         [0030]    The liquid crystal display panel  59  attaches an active matrix board  51  that includes switching elements such as a TFT (Thin Film Transistor) and the like to an opposite board  52  opposing the active matrix board  51  by means of a seal material (not shown). And, liquid crystal (not shown) is injected into a gap between both boards  51  and  52 . 
         [0031]    Here, a light polarization film  53  is disposed on a light receiving side of the active matrix board  51  and an output side of the opposite board  52 . And, the above liquid crystal display panel  59  makes use of a change in light transmittance due to an inclination of liquid crystal molecules, thereby displaying an image. 
         [0032]    Next, the backlight unit  49 , which is situated right under the liquid crystal display panel  59 , is described. The backlight unit  49  includes: an LED module (light emitting module) MJ; a diffusion plate  43 ; and a brightness improvement film  44  (here, a housing that houses these members is called a backlight chassis  42 ). 
         [0033]    The LED module MJ includes: LEDs (Light Emitting Diode)  21  that are each a light emitting element which defines a point light source; and a mount board  11  on which the LEDs are mounted. Details of these are described later. 
         [0034]    The diffusion plate (diffusion member)  43  is a plate-shaped optical member that overlies a mount board surface  11 U (mount surface  11 U of the mount board  11 ) crammed with the LEDs  21 , receives the light emitted from the LED module MJ, and diffuses the light. In other words, the diffusion plate  43  diffuses area light formed by the plurality of the LED modules MJ and spreads the light throughout the entire region of the liquid crystal display panel  59 . 
         [0035]    The brightness improvement film (brightness improvement member)  44  is, for example, an optical member that has a prism shape on a sheet surface, deflects a light radiation characteristic, and is situated to cover the diffusion plate  43 . Because of this, this brightness improvement film  44  collects the light traveling from the diffusion plate  43  to improve brightness. 
         [0036]    And, the above backlight unit  49  transmits the area light (backlight) formed by the LED module MJ through the plurality of the optical members  43  and  44 , and supplies the light to the liquid crystal display panel  59 . In this way, the liquid crystal display panel  59  of non-light emitting type receives the backlight from the backlight unit  49  and improves a display function. 
         [0037]    Here, the LED module MJ is described in detail by means of  FIG. 1 .  FIG. 1  is a plan view that shows chiefly the LED module MJ of the backlight unit  49 . As shown in this figure, the backlight unit  49  is crammed with the LEDs  21  (here, in  FIG. 1 , a connector  35  and the like described later are skipped for the sake of convenience). 
         [0038]    In detail, the LED  21  is mounted on the mount board piece  12 . Here, an aggregate composed of four mount board pieces  12  is defined as the mount board  11 . And, as the shape of the mount board  11 , as shown in  FIG. 2A  to  FIG. 2G , there are a plurality of kinds of shapes (here, the shape is a shape of the entire mount board  11  that changes in accordance with a way of arrangement of the mount board piece  12 ). 
         [0039]      FIG. 2A  shows the mount board  11  in which the four mount pieces  12 , on each of which the LED  21  is mounted, are arranged in a line like a Roman letter I (here,  FIG. 3  is an enlarged plan view of the mount board piece  12 ). Here, a way of connecting the mount board pieces  12  to one another is not especially limited; for example, they may be bonded by means of an adhesive or fixed by means of a fixing tool. 
         [0040]      FIG. 2B  shows the mount board  11  in which the four mount board pieces  12 , on which the LED  21  is mounted, are arranged like a Roman letter L.  FIG. 2C  shows the mount board  11  that has a shape obtained by turning over the L-shaped (first L shape) mount board  11  shown in  FIG. 2B . Here, the turned-over L shape shown in  FIG. 2C  is called a second L shape. Here, as shown in  FIG. 2B  and  FIG. 2C , a portion of a circumference of the mount board  11  defines an L-shaped portion (L-shaped portion  11 L) that encloses a neighboring mount board  11 . 
         [0041]      FIG. 2D  shows the mount board  11  having a step shape in which the four mount board pieces  12  are arranged so as to form an upward step from a left side to a right side of the figure.  FIG. 2E  shows the mount board  11  that has a shape obtained by turning over the step-shaped (first step shape) mount board  11  shown in  FIG. 2D . Here, the turned-over step shape, that is, the step shape, which forms an upward step from the right side to the left side of the figure, is called a second step shape. Here, as shown in  FIG. 2D  and  FIG. 2E , a portion of a circumference of the mount boards  11  defines the L-shaped portion  11 L that encloses a neighboring mount board  11 . 
         [0042]      FIG. 2F  shows the mount board  11  in which the four mount pieces  12 , on each of which the LED  21  is mounted, are arranged like a Roman letter T.  FIG. 2G  shows the mount board  11  in which the four mount board pieces  12  are arranged in a quadrangular shape. Here, as shown in  FIG. 2F , a portion of a circumference of the mount board  11  defines the L-shaped portion  11 L that encloses a neighboring mount board  11 . 
         [0043]    The shape of each of the mount boards  11  shown in  FIG. 2A  to  FIG. 2G  is formed by the aggregate of the four mount board pieces  12  that have shapes (square) identical to one another. These shapes are called a polyomino (a polygon formed by connecting edges of a plurality of squares to one another). Especially, the shapes of the mount boards  11  shown in  FIG. 2A  to  FIG. 2G  are each one of seven kinds of one-side tetrominos (a way of expressing a one-side tetromino is described later). 
         [0044]    Accordingly, as shown in  FIG. 1 , in case where a plurality of the mount boards  11  are disposed with no gap so as to be in tight contact with one another (laid with no gap), a large mount board  11  is formed (here, the aggregate of the mount boards  11  gathered so as to be in tight contact with one another is called a mount board unit  13 ). And, the shape of the mount board  11  is a polyomino, and it is sayable that at least one kind of shape includes the portion  11 L having the L shape defined by a portion of the circumference of the mount board  11  (here, the L-shaped portion  11 L is formed by edges of a plurality of the mount board pieces  12  intersecting each other). 
         [0045]    As described above, when the L-shaped portion  11 L defined by the circumference of the mount board  11  is formed, the mount board  11  including the portion  11 L is situated so as to fit another mount board  11  in the L-shaped portion  11 L. Accordingly, of the neighboring mount boards  11 , even if a try is performed to move one mount board  11  to the L-shaped portion  11 L, the one mount board  11  comes into contact with the other mount board  11  that includes the L-shaped portion  11 L and does not move. 
         [0046]    As a result of this, each mount board  11  becomes unlikely to deviate in surface directions (in short, in all directions of the board surface) in the board surface of the large mount board  11 . In detail, even if one mount board  11  tries to move, other mount boards  11  restrict the one mount board  11  to stop the movement. Accordingly, each mount board  11  becomes unlikely to deviate. 
         [0047]    For example, in case where individual mount board pieces  12  are gathered to form a large mount board  11  without being in contact with one another (in short, in case where the mount board pieces  12  are disposed in a matrix shape), if one mount board piece  12  tries to move, for example, along orthogonal two directions (X direction, Y direction) of the mount board piece  12 , also other mount board pieces  12  in contact with the one mount board piece move as a whole. 
         [0048]    However, when the mount board pieces  12  having various kinds of shapes are gathered to form the large mount board  11  as shown in  FIG. 1 , even if one mount board  11  tries to move in the orthogonal two directions (X direction, Y direction) of the mount board piece  12 , other mount boards  11  restrict the one mount board  11  to stop the movement. Because of this, the plurality of mount boards  11  do not deviate from the rest of the mount boards  11  as a whole. In other words, in this backlight unit  49 , the mount boards  11  are stably disposed without deviating (in short, the strength of the mount board unit  13  increases). 
         [0049]    Besides, it is sayable that each mount board  11  shown in  FIG. 2A  to  FIG. 2G  has a shape capable of restricting. In other words, each mount board  11  shown in  FIG. 2A  to  FIG. 2G  has no dedicated portions, for engagement between the mount boards  11 , such as a concave portion and a convex portion that are formed on a dedicated engagement portion, for example, a portion of the circumference (especially, one circumference of the mount board piece  12 ) of each mount board  11  and are capable of restricting. Accordingly, there is no unnecessary portion (e.g., the concave and convex portions shown in  FIG. 6B ) on the mount board piece  12 , and the large mount board  11  becomes relatively the smaller because there is no such unnecessary portion. 
         [0050]    In the meantime, the LED  21 , as shown in  FIG. 3 , has an anode (positive electrode)  31  and a cathode (negative electrode)  32 . And, the anode  31  and the cathode  32  connect to a connector  35  via a connection line  33  ( 33 A,  33 B). This connector  35  includes three terminals  36  ( 36 B,  36 A,  36 B) parallel with one another. Of the three terminals  36  parallel with one another, a central terminal  36  is a positive terminal  36  A, and both terminals  36  are negative terminals  36 B (here, a connection line for electrically connecting the anode  31  and the positive terminal  36 A to each other is indicated by  33 A and a connection line for connecting the cathode  32  and the negate terminals  36 B is indicated by  33 B). 
         [0051]    And, the connector  35 , which includes: the positive terminal  36 A for electrically connecting the LED  21  and the anode  31  to each other; and the negative terminal  36 B for connecting the LED  21  and the cathode  32  to each other, is mounted on the circumference of the mount boards  11  having the various shapes; and the identical electrode terminals  36  of the connectors  35  of neighboring mount boards  11  are electrically connected to each other. In detail, in the case where the mount boards  11  are disposed so as to be in tight contact with one another, the connectors  35  (in short, the identical electrode (positive or negative) terminals  36 ) are disposed so as to face each other and to be connectable physically and electrically to each other. 
         [0052]    For example, the connector  35  is mounted on every circumference of the mount board pieces  12  corresponding to the circumference of the mount board  11  (see  FIG. 2A  to  FIG. 2G ). According to this, as shown in  FIG. 4A  and  FIG. 4B , when a positive power supply terminal  71 A of a power supply  71  is electrically connected to the positive terminal  36 A of the connector  35  and a negative power supply terminal  71 B of the power supply  71  is electrically connected to the negative terminal  36 B of the connector  35  via a connection line  72 , a current flows into the LED  21 . 
         [0053]    Especially, even if the mount boards  11  having the different kinds of shapes are disposed so as to be in contact with one another as shown in  FIG. 4A  and the mount boards  11  having the identical kind of shape are disposed so as to be in contact with one another as shown in  FIG. 4B , when a current is supplied to any one of the connectors  35 , the LEDs  21  are connected in parallel and receive the current (in other words, in the large mount boards  11 , a circuit structure for supplying a current becomes simple). 
         [0054]    In short, no matter how the mount boards  11  shown in  FIG. 2A  to  FIG. 2G  are disposed, when the mount boards  11  are in tight contact with one another as if they grip one another, the connectors  35  are electrically connected to each other, whereby a current is supplied to the LEDs  21 . In addition, to whichever connector  35  the power supply  71  is connected, the current is supplied to all the LEDs  21 . 
       Other Embodiments 
       [0055]    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. 
         [0056]    For example, in  FIG. 1  described above, the plurality of mount boards  11  disposed so as to be in tight contact with one another include the mount boards  11  having the identical kind of shape and the mount boards  11  having the different kinds of shapes mingled with each other. However, without being limited to this, for example, as shown in  FIG. 4A , only the mount boards  11  having the different kinds of shapes may be gathered to be in tight contact with one another; and as shown in  FIG. 4B , only the mount boards  11  having the identical kind of shape may be gathered to be in tight contact with one another. 
         [0057]    In other words, the mount boards  11  having the identical kind of shape and the mount bards  11  having the different kinds of shapes may mingle with each other; only the mount boards  11  having the different kinds of shapes may be used; and the mount boards  11  having the identical kind of shape may be used. In short, the various mount boards  11  are usable in accordance with the size of the backlight unit  49 . 
         [0058]    Besides, in the above description, the mount board pieces  12  of the mount board  11  have the identical shape (square as the singe kind) as shown in  FIG. 2A  to  FIG. 2G ; however, this is not limiting. For example, the square shape mount board pieces  12  and the rectangular shape mount board pieces  12  may be included (in short, various kinds of the mount board pieces  12  are gathered) to form the mount board  11 . Of course, the mount board pieces  12  having other shapes may be gathered to form the mount boards  11  having the shapes shown in  FIG. 2A  to  FIG. 2G . 
         [0059]    Besides, in  FIG. 1 , the shape of the plurality of mount boards  11  disposed to be in tight contact with one another is a rectangular shape. However, according the mount boards  11  shown in  FIG. 2A  to  FIG. 2G , the shape of a plurality of the mount boards  11  disposed to be in tight contact with one another becomes a shape as well other than the rectangular shape. Because of this, the mount board unit  13  is compatible with variously shaped backlight units  49 . 
         [0060]    Besides, in the above description, one LED  21  is mounted on every mount board piece  12 ; however, this is not limiting. For example, a plurality of the LEDs  12  may be mounted on one mount board piece  12  (in short, at least one LED  21  may be disposed on the mount board piece  12 ). If such mount board piece  12  on which the plurality of LEDs  21  are mounted is used, a density (distribution density) of the LEDs  21  in the backlight unit  49  is suitably changed. 
         [0061]    For example, humans often have their eyes on the center of the liquid crystal display panel; accordingly, there is case where the center is brightened compared with the other portions of the liquid crystal display panel. In such case, when the mount board  11  including the mount board pieces  12  on which a plurality of the LEDs  21  is used, it is possible to dispose the LEDs  21  more tightly near the center of the mount board unit  13  corresponding to the center of the liquid crystal display panel than the other portions. 
         [0062]    Besides, as shown in  FIG. 2A  to  FIG. 2G , by changing the way of connecting the four mount board pieces  12 , the mount boards  11  having the seven kinds of shapes are formed. However, this is not limiting. For example, the mount boards  11  (e.g., the mount board  11  having twelve kinds of both-side pentominos), in which five square shape mount board pieces  12  are connected in various shapes, may be disposed so as to be in tight contact with one another. 
         [0063]    Here, the tetromino and the pentomino are each a kind of polyomino (a polygon formed by connecting edges of a plurality of squares to one another); the shape of the mount board  11  formed by the four mount board pieces  12  is called the tetromino; and the shape of the mount board  11  formed by the five mount board pieces  12  is called the pentomino Besides, in case where the shape of the mount board  11  is expressed under a rule that “shapes, which are identical to each other only when they are turned over, are different from each other,” it is expressed as “one side”; and in case where the shape of the mount board  11  is expressed under a rule that “shapes, which are identical to each other only when they are turned over, are identical to each other,” it is expressed as “both sides”. 
         [0064]    Besides, in the above description, as an example of the digital signage, the display device  69  mounted on the building is described; however, this is not limiting. For example, even the display device  69  mounted on a wall surface in a train is sayable to be a digital signage. Here, the above backlight unit  49  is usable for not only the digital signage but also a liquid crystal display device that is used chiefly for a household. 
         [0065]    Besides, the light color emitted from the LED  21  is not especially limited. For example, the LED  21  for emitting red light, the LED  21  for emitting green light, and the LED  21  for emitting blue light may mingle with one another to mix colors so as to generate white light or may generate light having other colors (single color light or mixed color light). In short, the backlight unit  49  may be a full-color light emitting device (light source device). OF course, all the LEDs  21  may be the LED  21  for emitting white light. 
         [0066]    Here, it is desirable that a predetermined amount of power is sufficiently supplied to the LED  21 . Because of this, it is desirable that the LED  21  is connected, for example, to a not-shown supplied power adjustment device (power adjustment portion) that is incorporated in the backlight unit  49 . 
       REFERENCE SIGNS LIST 
       [0067]      11  mount board 
         [0068]      11 L L-shaped portion 
         [0069]      12  mount board piece 
         [0070]      13  mount board unit 
         [0071]      21  LED (point light source, light emitting element) 
         [0072]      31  anode (positive electrode) 
         [0073]      32  cathode (negative electrode) 
         [0074]      33  connection line 
         [0075]      35  connector 
         [0076]      36  terminal 
         [0077]      36 A positive terminal 
         [0078]      36 B negative terminal 
         [0079]      43  diffusion plate (diffusion member) 
         [0080]      44  brightness improvement film (brightness improvement member) 
         [0081]      49  backlight unit 
         [0082]      69  display device 
         [0083]      71  power supply 
         [0084]      72  connection line