JP2013026528A - Light emitting device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device which efficiently radiates heat without accumulating heat in the device, and to provide a display device including the light emitting device.SOLUTION: A backlight unit 1 includes: a frame member 13 having a plate like bottom part 131; multiple printed boards 12 disposed on the bottom part 131; multiple LED chips 111a respectively aligned on the printed boards 12; and multiple reflection members 113 respectively provided on the printed boards 12 so as to enclose the LED chips 111a. The multiple printed boards 12 are disposed on the bottom part 131 of the frame member 13 so as to be spaced a first distance Iaway from each other in a first direction Xand be spaced a second distance Iaway from each other in a second direction Xthat intersects with the first direction X.

Description

  The present invention relates to a light emitting device provided in a backlight unit that irradiates light on the back surface of a display panel, and a display device including the light emitting device.

  In the display panel, liquid crystal is sealed between two transparent substrates, and when a voltage is applied, the orientation of the liquid crystal molecules is changed and the light transmittance is changed to optically display a predetermined image or the like. Is done. In this display panel, since the liquid crystal itself is not a light emitter, for example, the back side of the transmissive display panel is irradiated with light using a cold cathode tube (CCFL), a light emitting diode (LED), or the like as a light source. A backlight unit is provided.

  In the backlight unit, light sources such as cold-cathode tubes and LEDs are arranged on the bottom surface to emit light, and light sources such as cold-cathode tubes and LEDs are arranged on the edge of a transparent plate called a light guide plate. There is an edge light type that emits light to the front surface by dot printing or pattern shape provided on the back surface through light from the light plate edge.

  LEDs have excellent characteristics such as low power consumption, long life, and reduced environmental load by not using mercury, but they are expensive in price and white LEDs are indispensable until blue LEDs are invented. The use of the backlight unit as a light source was delayed due to the absence of the light source and the strong directivity. However, in recent years, high color rendering high-intensity white LEDs for lighting applications have been rapidly spread, and the LEDs have become cheaper along with them. Therefore, as a light source of a backlight unit, a transition from a cold cathode tube to an LED has been made. Is progressing.

  Since the LED has strong directivity, the edge light type is more effective than the direct type from the viewpoint of irradiating light so that the luminance of the surface of the display panel is uniform in the surface direction. However, the edge light type backlight unit has a problem that heat generated by the light source is concentrated due to the light source being concentrated on the edge portion of the light guide plate, and the bezel portion of the display panel is enlarged. Arise. Furthermore, the edge light type backlight unit has a great restriction on partial dimming control (local dimming), which is attracting attention as a control method capable of improving the quality and power saving of a display image. There is a problem that it is not possible to control a small divided area where high quality and power saving can be achieved.

  Therefore, in a direct-type backlight unit that is advantageous for partial dimming control, even when an LED with strong directivity is used as the light source, light is irradiated onto the display panel so that the luminance is uniform. There are ongoing studies of possible ways to do this.

  For example, in Patent Document 1, a display panel is divided into a plurality of rectangular areas, and a plurality of light source units corresponding to the respective rectangular areas are connected so that dimming control can be performed for each of the divided rectangular areas. A backlight unit is disclosed. In the backlight unit disclosed in Patent Document 1, each light source unit has a rectangular frame formed in a size corresponding to a rectangular area of the display panel, and a light emitting surface at the center of the bottom of the rectangular frame. The light-emitting element is configured to include an upward-facing light-emitting element, and a light-guide reflector that is disposed directly above the light-emitting element and has an inverted conical shape with the apex facing downward.

  In the technique disclosed in Patent Document 1, light having a strong directivity emitted from a light emitting element is diffused in a direction intersecting the optical axis of the light emitting element by a light guide reflector so that the amount of light is uniform in the surface direction. The display panel can be irradiated with the emitted light.

JP 2010-238420 A

  However, in the technique disclosed in Patent Document 1, since the plurality of light source units are each partitioned by a rectangular frame, heat generated by light emission from the light-emitting elements tends to stay in each rectangular frame. turn into. As described above, when heat is accumulated, output efficiency in a circuit for supplying power to the light emitting element may be reduced, and the life of the light emitting element may be shortened.

  Accordingly, an object of the present invention is to provide a light emitting device used in a backlight unit of a display device including a display panel, which can efficiently dissipate heat without stagnation of heat in the device, and the light emitting device. A display device is provided.

The present invention includes a casing composed of a frame part and a rectangular plate-shaped bottom part surrounded by the frame part,
A plurality of rectangular plate-like substrates arranged at the bottom with a first interval in the first direction and a second interval in a second direction orthogonal to the first direction;
A plurality of light emitting elements that emit light and are arranged at equal intervals in the second direction on each of the substrates;
A plurality of reflections provided on each substrate so as to surround each of the plurality of light emitting elements disposed on each substrate, extending toward both sides in the first direction of each substrate, and having a polygonal outer peripheral shape. A light emitting device including the member.

  Further, in the light emitting device of the present invention, the end surfaces of the end portions of the substrates facing each other with a second interval are spaced apart from each other in the first direction of the substrate toward the other side portion. It is formed.

  In the light-emitting device of the present invention, the end surfaces of the end portions of the substrates facing each other at a second interval are formed to be curved in a convex shape in directions close to each other.

  In the light-emitting device of the present invention, a drive signal input unit for inputting a drive signal to each light-emitting element disposed on each substrate is provided at one end in the second direction of each substrate. And

  Further, in the light emitting device of the present invention, at least some of the substrates that form a pair spaced apart in the second direction at a second interval are such that each end facing each other has a central portion in the second direction of the bottom It arrange | positions so that it may be located on both sides of this.

  Further, in the light emitting device of the present invention, each reflecting member surrounding each light emitting element arranged at a position closest to each end facing each other with a second interval between each substrate has each side facing each other. It protrudes away from the substrate and is formed to be continuous with each other.

The present invention also provides a display panel,
A display device comprising: the light emitting device that irradiates light on a back surface of the display panel.

  According to the present invention, the light-emitting device includes a plurality of rectangular plate-like substrates disposed at the bottom of the housing, a plurality of light-emitting elements arranged in alignment on each substrate, and each substrate surrounding each light-emitting element. And a plurality of reflecting members provided on the top. The plurality of substrates are arranged at the bottom of the housing with a first interval in the first direction and a second interval in a second direction orthogonal to the first direction. Each light emitting element is arrange | positioned on each board | substrate at equal intervals in the 2nd direction of each board | substrate. Each reflecting member extends to both sides in the first direction of each substrate, and the outer peripheral shape is a polygonal shape.

  The heat generated when the light emitting element emits light exists in the vicinity of the light emitting element such as air existing between the reflecting member extending from both sides in the first direction of each substrate and the bottom of the housing. Warm up the air.

  In the light emitting device of the present invention, each substrate interposed between the bottom of the housing and the reflecting member has a first interval in the first direction and a second interval in the second direction orthogonal to the first direction. Since the opening is disposed at the bottom of the casing, the heated air existing between the bottom of the casing and the reflecting member faces each other of the substrates spaced apart from each other with a first interval in the first direction. A space formed between the side portions (hereinafter referred to as “first heat dissipation space”) and each end portion of the substrates that are spaced apart from each other with a second interval in the second direction. Flow (hereinafter referred to as “second heat radiation space”) without staying. Therefore, heat can be efficiently radiated without heat remaining in the light emitting device.

  According to the invention, the end surfaces of the end portions facing each other with a second interval between the substrates are formed so as to be spaced apart from each other in the first direction of the substrate toward the other side portion. . When the light emitting device is arranged and used so that the first direction is parallel to the vertical direction and the first direction side of the substrate is on the upper side in the vertical direction, the airflow flowing through the second heat radiation space is Since the one-direction other side portion side flows to the one side portion side and the space width side to the narrow side, the flow velocity increases. Thereby, it is possible to more effectively suppress heat from staying in the light emitting device, and to efficiently dissipate heat.

  Further, according to the present invention, the end surfaces of the end portions facing each other with a second interval between the substrates are formed to be curved in a convex shape in the direction of approaching each other. As a result, it is possible to prevent the airflow flowing through the second heat dissipation space from becoming turbulent, and thus it is possible to more effectively suppress heat from being retained in the light emitting device, and to efficiently dissipate heat. Can do.

  Further, according to the present invention, one end of each substrate in the second direction, specifically, each of the substrates spaced apart from each other in the second direction with a second interval, facing each other with a second interval A drive signal input unit for inputting a drive signal to each light emitting element disposed on each substrate is provided at the end on the opposite side. Accordingly, since the drive signal input unit is not provided in the second heat radiation space for radiating the heat in the apparatus, the airflow in the second heat radiation space can be made smooth.

  Further, according to the present invention, at least some of the substrates that are separated from each other with a second interval in the second direction are opposite to each other, and each of the opposite end portions is a central portion in the second direction at the bottom of the casing. It is arrange | positioned at the bottom part so that it may be located on both sides. In the light emitting device configured as described above, the second heat radiating space is formed at the center in the second direction of the bottom portion of the housing, so that the warming that exists between the bottom portion of the housing and the reflecting member is heated. The air flowing in the center in the second direction at the bottom of the housing can radiate heat in the light emitting device. For example, in a light emitting device as a backlight unit provided in a display device such as a general-use television receiver, the shape corresponds to the central portion of the bottom portion of the housing set to a shape and size corresponding to the display panel. The emission intensity of the region is increased. In such a case, heat tends to stay in the central portion of the bottom portion of the housing. However, by forming the second heat radiation space in the region corresponding to the central portion in the second direction of the bottom portion of the housing, the heat can be efficiently obtained. It can dissipate heat.

  According to the present invention, each reflecting member surrounding each light emitting element disposed at a position closest to each end facing each other with a second interval between each substrate has each side facing each other separated from each substrate. The ridges are spaced apart and are formed to be continuous with each other. In the light emitting device configured as described above, the protruding portion of the reflecting member that protrudes away from each substrate is positioned in the vicinity of the opposing ends of each substrate that is spaced apart from each other by the second interval in the second direction. Will do. As a result, the space formed by the raised portions separated from the respective substrates of the reflecting member is also included in the second heat radiation space. Therefore, since the flow of the airflow in the second heat radiation space can be made smooth, it is possible to more effectively suppress heat from staying in the light emitting device, and heat can be efficiently radiated.

  Further, according to the present invention, the display device includes the light emitting device according to the present invention, which can efficiently dissipate heat without stagnation in the device, so that a high-quality image can be displayed over a long period of time. Can be displayed on the panel.

It is a disassembled perspective view which shows the structure of the liquid crystal display device 100 which concerns on one Embodiment of this invention. It is a figure which shows typically the cross section of the liquid crystal display device 100 when it cut | disconnects by the cut surface line AA in FIG. It is a figure which shows the base 111 and LED chip 111a. It is a figure which shows the LED chip 111a and the base 111 which were mounted in the printed circuit board 12. It is a figure which shows the positional relationship of the LED chip 111a supported by the base 111, and the lens 112. FIG. It is a figure for demonstrating the optical path of the light radiate | emitted from the LED chip 111a. It is a figure which shows the structure of the reflection member 113 with which the light emission part 11 is provided. It is a figure for demonstrating a mode that the heat which generate | occur | produced from LED chip 111a is thermally radiated. Is a perspective view showing an enlarged one another of each end portion opposite configuration of the printed circuit board 12 away at a second distance I ₂ in the second direction X _2. Is a view showing the shape of the end face of each of opposite ends of each print board 12 spaced apart a second distance I ₂ in the second direction X _2. Is a view showing the shape of the end face of each of opposite ends of each print board 12 spaced apart a second distance I ₂ in the second direction X _2. In the backlight unit 60 is an exploded perspective view showing an enlarged configuration of each end portion opposed to each other of each print board 12 to be separated in the second direction X ₂ at a second distance I _2. In the backlight unit 60 is a perspective view showing an enlarged configuration of each end portion opposed to each other of each print board 12 to be separated in the second direction X ₂ at a second distance I _2.

  FIG. 1 is an exploded perspective view showing a configuration of a liquid crystal display device 100 according to an embodiment of the present invention. FIG. 2 is a diagram schematically showing a cross section of the liquid crystal display device 100 when cut along the cutting plane line AA in FIG.

  The liquid crystal display device 100 which is a display device of the present invention is a device that displays an image on a display screen by outputting image information in a television receiver or a personal computer. The display screen is formed by a liquid crystal panel 2 that is a transmissive display panel having liquid crystal elements, and the liquid crystal panel 2 is formed in a rectangular flat plate shape. In the liquid crystal panel 2, two surfaces in the thickness direction are a front surface 21 and a back surface 22. The liquid crystal display device 100 displays an image so as to be visible when viewed from the front surface 21 toward the rear surface 22.

  The liquid crystal display device 100 includes a liquid crystal panel 2 and a backlight unit 1 that includes a plurality of light emitting units 11 and is a light emitting device according to the present invention.

  The liquid crystal panel 2 is supported by the side wall portion 132 in parallel with the bottom surface 131a of the bottom portion 131 of the frame member 13 which is a casing that is provided in the backlight unit 1 and includes a frame portion and a bottom portion 131 surrounded by the frame portion. The liquid crystal panel 2 includes two substrates and is formed in a rectangular plate shape when viewed from the thickness direction. The liquid crystal panel 2 includes a switching element such as a TFT (Thin Film Transistor), and liquid crystal is injected into the gap between the two substrates.

  The liquid crystal panel 2 exhibits a display function by being irradiated with light from the backlight unit 1 disposed on the back surface 22 side as a backlight. The two substrates are provided with drivers (source drivers) for driving the pixels in the liquid crystal panel 2, various elements, and wirings.

  In the liquid crystal display device 100, a diffusion plate 3 is disposed between the liquid crystal panel 2 and the backlight unit 1 in parallel with the liquid crystal panel 2. This diffusion plate 3 becomes an irradiated body. A prism sheet (not shown) may be disposed between the liquid crystal panel 2 and the diffusion plate 3.

  The diffusion plate 3 prevents the brightness from being locally biased by diffusing the light emitted from the backlight unit 1 in the surface direction. The prism sheet directs the traveling direction of the light reaching from the back surface 22 side through the diffusion plate 3 to the front surface 21 side. In the diffusing plate 3, in order to prevent the luminance from being biased in the surface direction, the traveling direction of light includes a lot of components in the surface direction as vector components. On the other hand, the prism sheet converts the traveling direction of light containing a lot of vector components in the surface direction into the traveling direction of light containing many components in the thickness direction. Specifically, the prism sheet is formed with a large number of lens or prism-shaped portions arranged in the plane direction, thereby reducing the diffusion of light traveling in the thickness direction. Therefore, the luminance can be increased in the display by the liquid crystal display device 100.

  The backlight unit 1 is a direct type backlight device that irradiates the liquid crystal panel 2 with light from the back surface 22 side. The backlight unit 1 includes a plurality of light emitting units 11 that irradiate light to the liquid crystal panel 2 through the diffusion plate 3, a plurality of printed circuit boards 12, and a frame member 13.

  The frame member 13 is a basic structure of the backlight unit 1, and has a rectangular flat plate-shaped bottom portion 131 that faces the liquid crystal panel 2 at a predetermined interval, and a side wall portion 132 that continues to the bottom portion 131 and rises from the bottom portion 131. Consists of. The bottom 131 is formed in a rectangular shape when viewed from the thickness direction, and its size is slightly larger than that of the liquid crystal panel 2. The side wall part 132 is formed to rise from the two end parts forming the short side of the bottom part 131 and the two end parts forming the long side to the front surface 21 side of the liquid crystal panel 2. As a result, four flat side wall portions 132 are formed around the bottom portion 131.

  The printed circuit board 12 is fixed to the bottom 131 of the frame member 13. The printed circuit board 12 is, for example, a substrate made of glass epoxy having conductive layers formed on both sides. In this embodiment, each printed circuit board 12 is formed in a rectangular plate shape, and its long side (longitudinal direction) is parallel to the long side direction of the bottom part 131, and the short side (width direction) is the short side direction of the bottom part 131. It arranges in the bottom part 131 so that it may become parallel.

Will be described later for details of the arrangement for the bottom 131 of the plurality of printed circuit board 12, a plurality of printed circuit board 12 includes a first spaced I ₁ in the first direction X _1, and perpendicular to the first direction X ₁ in the second direction _{X 2} at a second interval _{I 2,} are located at the bottom 131 of the frame member 13. In the present embodiment, the first direction X ₁ is parallel to the short side direction of the bottom 131 of the frame member 13, and the second direction X ₂ is parallel to the long side of the bottom 131. On each printed circuit board 12, a plurality of light emitting portions 11 are provided at equal intervals in a direction parallel to the second direction X _2.

The plurality of light emitting units 11 irradiate the liquid crystal panel 2 with light through the diffusion plate 3. In the present embodiment, a plurality of printed circuit boards 12 provided with a plurality of light emitting units 11 are disposed so as to face the entire back surface 22 of the liquid crystal panel 2 through the diffusion plate 3 with the plurality of light emitting units 11 as one group. By arranging in parallel, the light emitting units 11 are provided in a matrix. Each light emitting unit 11 is formed in a square shape when viewed from the side of the diffuser plate 3 that is an object to be irradiated, that is, when viewed from a direction perpendicular to the bottom 131 of the frame member 13, and on the liquid crystal panel 2 side of the diffuser plate 3. The luminance on the surface is defined to be 5000 cd / m ^2, and the length of one side is, for example, 55 mm.

  Each of the plurality of light emitting units 11 includes a light emitting diode (LED) chip 111a that is a light emitting element, a base 111 that supports the LED chip 111a, a lens 112 that is an optical member, and a reflecting member 113.

  FIG. 3 is a diagram showing the base 111 and the LED chip 111a. 3A is a plan view, FIG. 3B is a front view, and FIG. 3C is a bottom view.

  The base 111 is a member for supporting the LED chip 111a and is made of resin. The base 111 has a square support surface for supporting the LED chip 111a, and the length L1 of one side of the square is, for example, 3 mm. Moreover, the height of the base 111 is 1 mm, for example.

  As shown in FIG. 3, the base 111 includes a base main body 111g made of ceramics and two electrodes 111c provided on the base main body 111g. The LED chip 111a includes a support surface of the base 111, The base body 111g is fixed to the center of the upper surface with an adhesive member 111f. The two electrodes 111c are spaced apart from each other, and are respectively provided over the top surface, the side surface, and the bottom surface of the base body 111g. Two terminals (not shown) of the LED chip 111a and the two electrodes 111c are connected by two bonding wires 111d, respectively. The LED chip 111a and the bonding wire 111d are sealed with a transparent resin 111e such as silicon resin.

  FIG. 4 is a view showing the LED chip 111 a and the base 111 mounted on the printed circuit board 12. The LED chip 111 a is mounted on the printed circuit board 12 via the base 111 and emits light in a direction away from the printed circuit board 12. The LED chip 111 a is located at the center of the base 111 when the light emitting unit 11 is viewed in plan from the diffuser plate 3 side, that is, when viewed from a direction perpendicular to the bottom 131 of the frame member 13. In the plurality of light emitting units 11, the light emission control by the LED chips 111 a can be controlled independently of each other. Thereby, the backlight unit 1 can perform partial dimming control (local dimming).

  When mounting the LED chip 111a and the base 111 on the printed circuit board 12, first, solder is respectively applied to the two connection terminal portions 121 of the conductive layer pattern included in the printed circuit board 12, and the base body is attached to the solder. The base 111 and the LED chip 111a fixed to the base 111 are placed on the printed circuit board 12 by, for example, an automatic machine (not shown) so that the two electrodes 111c provided on the bottom surface of 111g match each other. The printed circuit board 12 on which the base 111 and the LED chip 111a fixed to the base 111 are placed is sent to a reflow tank that irradiates infrared rays, and the solder is heated to about 260 ° C. And are soldered.

  The LED chips 111a provided in each of the plurality of light emitting units 11 are arranged in a matrix when the light emitting unit 11 is viewed in plan view from the diffusion plate 3 side, that is, when viewed from a direction perpendicular to the bottom 131 of the frame member 13. The distance between the LED chips 111a that are arranged and adjacent to each other is the same in both the row direction and the column direction.

  FIG. 5 is a diagram showing a positional relationship between the LED chip 111 a supported by the base 111 and the lens 112.

  The lens 112 is provided in contact with the LED chip 111a by insert molding so as to cover the base 111 supporting the LED chip 111a, and reflects or refracts light emitted from the LED chip 111a in a plurality of directions. That is, the lens 112 diffuses light. The lens 112 is a transparent lens, and is made of, for example, silicon resin or acrylic resin.

  In the lens 112, the upper surface 112a, which is a surface facing the liquid crystal panel 2 through the diffusion plate 3, is curved with a recess in the center, and the side surface 112b is in a substantially cylindrical shape parallel to the optical axis S of the LED chip 111a. The diameter L2 in the cross section formed and orthogonal to the optical axis S is, for example, 10 mm, extends outward with respect to the base 111, and is lateral to the base 111 (perpendicular to the support surface of the base 111. The four surfaces are provided so as to cover at least a part thereof. That is, the lens 112 is larger than the base 111 in the direction orthogonal to the optical axis S of the LED chip 111a (the diameter L2 of the lens 112 is larger than the length L1 of one side of the support surface of the base 111). As described above, the lens 112 is provided so as to extend outward with respect to the base 111, so that the light emitted from the LED chip 111a can be diffused by the lens 112 over a wide range.

  The height H1 of the lens 112 is 4.5 mm, for example, and is smaller than the diameter L2. In other words, the lens 112 has a length (diameter L2) in a direction orthogonal to the optical axis S of the LED chip 111a larger than the height H1. The light incident on the lens 112 is diffused in the direction intersecting the optical axis S inside the lens 112.

  As described above, the diameter L2 is set larger than the height H1 in order to reduce the thickness of the backlight unit 1 and to uniformly irradiate the liquid crystal panel 2 with light. In order to reduce the thickness of the backlight unit 1, it is necessary to reduce the height H1 of the lens 112, that is, to make the lens 112 as thin as possible. However, when the lens 112 is thinned, uneven illuminance tends to occur on the back surface 22 of the liquid crystal panel 2, and as a result, uneven brightness tends to occur on the front surface 21 of the liquid crystal panel 2. In particular, when the distance between the adjacent LEDs 111a is long, the area between the adjacent LED chips 111a on the back surface 22 of the liquid crystal panel 2 is far from the LED chip 111a, and the amount of irradiation light is reduced. Irradiance unevenness (brightness unevenness) is likely to occur between the region adjacent to the LED chip 111a.

  In order to irradiate the light emitted from the LED chip 111a to a region far from the LED chip 111a via the lens 112, it is necessary to increase the diameter L2 of the lens 112 to some extent. In this embodiment, the lens 112 By making the diameter L2 of the light source larger than the height H1, the backlight unit 1 can be made thinner and the liquid crystal panel 2 can be uniformly irradiated with light.

  If the diameter L2 of the lens 112 is made smaller than the height H1 of the lens 112, not only thinning and uniform irradiation become difficult, but also an insert for integrally molding the lens 112 and the LED chip 111a. In molding, there is a problem that the balance tends to be poor. Further, when soldering an integrally molded product including the LED chip 111a and the base 111b and the insert-molded lens 112 to the printed circuit board 12, the balance is easily lost, and there is a problem in assembly.

  The upper surface 112a of the lens 112 includes a central portion 1121, a first curved portion 1122, and a second curved portion 1123. In the lens 112, the curved upper surface 112a having a dent in the central portion is a first region that totally reflects the emitted light and emits it from the side surface 112b, and a second region that refracts the emitted light outward and emits it. And having a region. The first region is formed in the first curved portion 1122, and the second region is formed in the second curved portion 1123.

  The central portion 1121 is formed at the central portion of the upper surface 112a facing the liquid crystal panel 2 through the diffusion plate 3, and the center of the central portion 1121 (that is, the optical axis of the lens 112) is on the optical axis S of the LED chip 111a. Located in. The central portion 1121 is formed in a circular shape parallel to the light emitting surface of the LED chip 111a, and its diameter L3 is, for example, 1 mm.

  As another embodiment of the present invention, the central portion 1121 has a circular bottom surface instead of the circular shape, and a conical side surface protruding from the bottom surface toward the LED chip 111a. You may make it a shape.

  The central portion 1121 is formed to irradiate light to a region facing the central portion 1121 in the diffusing plate 3 that is an object to be irradiated. However, since the central portion 1121 is a portion facing the LED chip 111a, most of the light emitted from the LED chip 111a reaches the central portion 1121, and when most of the light is transmitted as it is, it faces the central portion 1121. The illuminance of the area to be markedly increased. Therefore, it is preferable that the shape of the central portion 1121 is the side shape of the cone. In the case of the conical side surface shape, most of the light is reflected by the central portion 1121 and less light is transmitted through the central portion 1121, so that the illuminance of the region facing the central portion 1121 can be suppressed.

  The first curved portion 1122 is connected to the outer peripheral edge of the central portion 1121 and extends outward in one direction of the LED chip 111a in the optical axis S direction (direction toward the liquid crystal panel 2). It is an annular curved surface curved so as to be convex. The shape of this curved surface is designed so that the light emitted from the LED chip 111a is totally reflected.

  More specifically, of the light emitted from the LED chip 111a, the light that has reached the first curved portion 1122 is totally reflected by the first curved portion 1122, and then passes through the side surface 112b of the lens 112, thereby reflecting the reflecting member 113. Head to. The light that has reached the reflecting member 113 is diffused by the reflecting member 113, and is irradiated on a region that is not opposed to the LED chip 111a in the diffusing plate 3 that is an object to be irradiated. Thereby, the irradiation light quantity to the area | region which is not facing LED chip 111a can be increased.

  The first curved portion 1122 is formed such that the incident angle of the light emitted from the LED chip 111a is equal to or greater than the critical angle φ in order to totally reflect the light emitted from the LED chip 111a. For example, when the lens 112 is made of an acrylic resin, the refractive index of the acrylic resin is “1.49” and the refractive index of air is “1”, so sinφ = 1 / 1.49. From this equation, the critical angle φ is 42.1 °, and the first curved portion 1122 is formed in a shape with an incident angle of 42.1 ° or more.

  The second curved portion 1123 is connected to the outer peripheral edge portion of the first curved portion 1122, extends toward the other side in the optical axis S direction of the LED chip 111a, and protrudes to one side in the optical axis S direction. It is a curved annular curved surface.

  Of the light emitted from the LED chip 111 a, the light that has reached the second curved portion 1123 is refracted and travels toward the diffuser plate 3 and the reflecting member 113 when passing through the second curved portion 1123. The light reaching the reflection member 113 is diffused and travels toward the diffusion plate 3. Thus, the light traveling toward the diffusion plate 3 by the second curved portion 1123 is mainly irradiated to a region different from the region irradiated with light by the central portion 1121 and the first curved portion 1122 in the diffusion plate 3. The amount of light is complemented. Since the second curved portion 1123 needs to transmit light, the incident angle is less than 42.1 ° so as not to totally reflect the light emitted from the LED chip 111a.

  As described above, the lens 112 is formed with the first curved portion 1122 that totally reflects the light emitted from the LED chip 111a toward the side surface 112b of the lens 112 at the outer peripheral edge portion of the central portion 1121. A second curved portion 1123 that refracts the light emitted from the LED chip 111a is formed at the outer peripheral edge of the curved portion 1122.

  The LED chip 111a generally has high directivity, the amount of light near the optical axis S is extremely large, and the amount of light decreases as the light emission angle with respect to the optical axis S increases. Therefore, in order to increase the amount of light emitted to the region relatively far from the optical axis S of the LED chip 111a (that is, the optical axis of the lens 112), light having a large emission angle with respect to the optical axis S is directed to this region. Instead, it is necessary to direct light having a small emission angle to this region.

  In the present embodiment, as described above, the first curved portion 1122 that totally reflects light toward the region is formed around the central portion 1121 through which the optical axis S passes. The amount of irradiation light can be increased.

  On the other hand, if the second curved portion 1123 is formed adjacent to the periphery of the central portion 1121, and the first curved portion 1122 is formed adjacent to the second curved portion 1123, The emission angle of the light toward the first curved portion 1122 with respect to the optical axis S increases, and as a result, the amount of light that is totally reflected by the first curved portion 1122 and applied to the region is reduced. As a result, the luminance in the diffusion plate 3 becomes non-uniform.

  FIG. 6 is a diagram for explaining an optical path of light emitted from the LED chip 111a. Light emitted from the LED chip 111 a enters the lens 112 and is diffused by the lens 112. Specifically, of the light incident on the lens 112, the light that has reached the central portion 1121 on the upper surface 112 a facing the liquid crystal panel 2 through the diffusion plate 3 is emitted in the direction of the arrow A 1 toward the liquid crystal panel 2. The light reaching the first curved portion 1122 is totally reflected and emitted from the side surface 112b in the direction of the arrow A2, and the light reaching the second curved portion 1123 is outward (a direction away from the LED chip 111a). The light is refracted and emitted toward the liquid crystal panel 2 in the direction of the arrow A3.

  In the present embodiment, the LED chip 111a and the lens 112 have the same optical axis, that is, the center of the lens 112 (that is, the optical axis of the lens 112) is positioned on the optical axis S of the LED chip 111a. In addition, the lens 112 is preliminarily aligned with high accuracy so as to contact the LED chip 111a.

  As a method of forming the LED chip 111a and the lens 112 by aligning them in advance, insert molding, a method of fitting the LED chip 111a supported by the base 111 to the lens 112 molded into a predetermined shape, etc. Can be mentioned. In the present embodiment, the LED chip 111a and the lens 112 are formed by being previously aligned by insert molding.

  When insert molding is performed, an upper surface mold and a lower surface mold are roughly used. Molding is performed by injecting a resin, which is a raw material of the lens 112, from a resin inlet into a space formed when the upper surface mold and the lower surface mold are combined. In addition, in a state where the LED chip 111a supported by the base 111 is held in a space formed when the upper surface mold and the lower surface mold are combined, a resin as a raw material of the lens 112 is injected from the resin injection port. You may make it shape | mold by doing.

  Thus, by forming the LED chip 111a and the lens 112 by insert molding, it is possible to align the lens 112 with high accuracy so that the lens 112 contacts the LED chip 111a.

  Thus, the backlight unit 1 can accurately reflect and refract the light emitted from the LED chip 111a through the lens 112 by the lens 112 in contact with the LED chip 111a. Even in the thinned liquid crystal display device 100 in which the distance H3 to the substrate 12 is small, the liquid crystal panel 2 can be irradiated with light through the diffusion plate 3 so that the luminance is uniform in the surface direction.

FIG. 7 is a diagram illustrating a configuration of the reflecting member 113 provided in the light emitting unit 11. Figure 7 is an enlarged view of each end portion opposed to each other of each print board 12 to be separated in the second direction X ₂ at a second distance I _2.

The reflection member 113 is provided around the base 111 on which the LED chip 111 a is supported, and reflects the light emitted from the lens 112 toward the liquid crystal panel 2 through the diffusion plate 3. The reflection member 113 has a polygonal shape, for example, a square shape, when viewed from the diffuser 3 side, that is, when viewed in plan in the direction of the optical axis S of the LED chip 111a. The reflective member 113 extends outwardly from the first widthwise side portions parallel to the direction X ₁ of the printed circuit board 12.

  In addition, when the reflecting member 113 is viewed in plan in the optical axis S direction of the LED chip 111a, each side of the outer peripheral shape is continuous with the adjacent reflecting member 113. As a result, the distance between the LED chips 111a is the same in the adjacent light emitting sections 11, so that the luminance uniformity on the surface of the diffusion plate 3 on the liquid crystal panel 2 side can be further improved.

  The reflecting member 113 is a flat plate-like base portion 1131 having an opening 113a at the center, specifically, a square flat plate-like base portion 1131 having a side length of 38.8 mm, and an outer peripheral edge portion surrounding the base portion 1131. And an inclined portion 1132 having an inclined surface that inclines so as to move away from the printed circuit board 12 as it moves away from the LED chip 111a. The reflecting member 113 configured by the base portion 1131 and the inclined portion 1132 is provided in an inverted dome shape with the LED chip 111a as the center.

  In the present embodiment, the reflecting member 113 has a square outer peripheral shape when viewed in plan in the direction of the optical axis S of the LED chip 111a, and is configured to be line-symmetric with respect to the square diagonal line. Further, the center point of the square shape is configured to be 90 ° rotationally symmetric.

The base 1131 is such that each side of the square shape when viewed in plan in the direction of the optical axis S of the LED chip 111a is in a matrix, that is, parallel to the row direction or column direction of the plurality of LED chips 111a arranged in alignment. Formed. The base 1131 is formed along the printed circuit board 12 and is provided with a circular opening 113a at the center when viewed in plan in the direction of the optical axis S. The diameter of the circular opening 113a is set to be slightly smaller than the diameter L2 of the lens 112, and the lens 112 is inserted through the opening 113a. The base 1131 and extends outward from the width direction parallel sides in the first direction X ₁ of the printed circuit board 12.

  The inclined portion 1132 is connected to each side portion of the outer peripheral shape of the base portion 1131, and has an inclined surface that extends so as to be separated from the printed circuit board 12 as it goes outward (in a direction away from the LED chip 111 a). An inclination angle θ1 between the inclined surface of the inclined portion 1132 and the printed circuit board 12 is, for example, 80 °. Further, the height H2 of the inclined portion 1132 in the direction of the optical axis S is, for example, 4 mm.

  In the present embodiment, a gap G is formed between the diffusion plate 3 and the far end of the reflecting member 113 with respect to the printed circuit board 12, that is, the tip of the inclined portion 1132 on the diffusion plate 3 side in the optical axis S direction. Is formed. In the light emitting unit 11, the amount of light tends to decrease as the distance from the LED chip 111a increases in the surface direction. By forming the gap G, a part of the light emitted from each other between the adjacent light emitting portions 11 can enter the gap G to compensate for a decrease in the amount of light. Therefore, the uniformity of the light quantity in the surface direction can be further improved.

  The base portion 1131 and the inclined portion 1132 are made of highly bright PET (Polyethylene Terephthalate), aluminum, or the like. High-brightness PET is foamable PET containing a fluorescent agent, and examples thereof include E60V (trade name) manufactured by Toray Industries, Inc. The thickness of the base 1131 is, for example, 0.1 to 0.5 mm.

  The reflection member 113 including the base portion 1131 and the inclined portion 1132 has a total reflectance of, for example, 80% to 100% with respect to visible light emitted from the LED chip 111a, and in this embodiment, 97%. is there. The total reflectance can be measured according to JIS-K-7375.

  The reflection members 113 configured as described above and provided in each of the plurality of light emitting units 11 are preferably formed integrally with each other. As a method of integrally molding the plurality of reflecting members 113, when the reflecting member 113 is made of high-brightness PET, extrusion molding and vacuum forming can be mentioned, and the reflecting member 113 is made of aluminum. If it is, press working can be mentioned.

  For example, when a plurality of reflecting members 113 made of high-brightness PET are integrally formed by vacuum forming, they are formed as follows.

  First, after a sheet made of high-brightness PET is softened by heating, it is fixed to the upper part of a mold having a large number of small holes (vacuum holes) for vacuum suction beforehand. Next, after the mold or sheet is moved and sealed between the sheet and the mold so that air does not leak, the internal air is rapidly removed through the vacuum hole. Since the inside of the sheet is depressurized, it is pressed onto the mold surface by atmospheric pressure, and the shape of the mold is faithfully reproduced. What was molded in this way can be taken out of the mold after cooling, and the integrally formed reflecting member 113 can be manufactured. By integrally forming the reflecting member 113 by such a processing method, the reflecting member 113 having the same thickness of the base portion 1131 and the inclined portion 1132 and having excellent thickness uniformity can be manufactured.

  By integrally forming the reflecting member 113 provided in each of the plurality of light emitting units 11, it is possible to improve the accuracy of the arrangement position of the plurality of light emitting units 11 with respect to the printed circuit board 12, and at the time of the assembly operation of the backlight unit 1, Since the number of operations for attaching the reflecting member 113 can be reduced, the efficiency of the assembly operation can be improved.

  The optical path of the light emitted from the LED chip 111a in the liquid crystal display device 100 including the backlight unit 1 configured as described above will be described with reference to FIG.

  In the backlight unit 1, of the light emitted from the LED chip 111 a and incident on the lens 112, the light reaching the central portion 1121 on the upper surface 112 a facing the liquid crystal panel 2 through the diffusion plate 3 is transmitted to the liquid crystal panel 2. The light emitted toward the arrow A1 and reaching the first curved portion 1122 is reflected and emitted from the side surface 112b in the arrow A2 direction, and the light reaching the second curved portion 1123 is refracted outward. Then, it is emitted toward the liquid crystal panel 2 in the direction of the arrow A3.

  Of the light emitted from the lens 112, the light emitted from the side surface 112 b (light whose emission direction intersects the optical axis S) is incident on the inclined portion 1132 of the reflecting member 113. The inclined portion 1132 of the reflecting member 113 extends away from the printed circuit board 12 as it goes outward (in the direction away from the LED chip 111a), so that the light incident on the inclined section 1132 is parallel to the printed circuit board 12. The amount of light in the region corresponding to the inclined portion 1132 in the surface direction can be increased.

  Next, a configuration for radiating heat generated from the LED chip 111a, which is a characteristic configuration in the backlight unit 1 of the present embodiment, will be described.

FIG. 8 is a diagram for explaining how heat generated from the LED chip 111a is dissipated. Figure 9 is a perspective view showing the expansion of the printed circuit board 12 to be separated in the second direction X ₂ at a second interval I _2, the configuration of each end portion facing each other with a second distance I ₂ It is.

In the present embodiment, as described above, the printed circuit board 12, between the bottom 131 and the reflection member 113 of the frame member 13, parallel to the width direction thereof to the first direction X _1, and the longitudinal direction of the second so as to be parallel to the direction X _2, it is aligned on the bottom 131 of the frame member 13. Then, a plurality of printed circuit board 12 includes a first spaced _{I 1} in the first direction _{X 1,} and, in a second direction _{X 2} perpendicular to the first direction _{X 1} at a second interval _{I 2,} frame member 13 at the bottom 131. In the present embodiment, a plurality of printed circuit board 12 is arranged in the second direction X ₂ in two rows.

The backlight unit 1 is coincident parallel width direction in the vertical direction in the first direction X ₁ of the printed circuit board 12, the longitudinal direction parallel to the second direction X ₂ is arranged to coincide in the horizontal direction Yes.

LED heat generated by the chip 111a emits a light reflecting member 113 and the printed circuit board 12 and conductive reflecting member extending from a first widthwise side portions parallel to the direction X ₁ of the printed circuit board 12 113 And the air existing around the LED chip 111a, such as the air existing between the bottom 131 of the frame member 13 and the like.

In the backlight unit 1 of the present embodiment, the printed circuit board 12 interposed between the bottom 131 and the reflection member 113 of the frame member 13, a first spaced I ₁ in the first direction X _1, and first Since it is arranged at the bottom 131 with a second interval I ₂ in the second direction X ₂ orthogonal to the direction X ₁ , the warm air existing between the bottom 131 of the frame member 13 and the reflecting member 113 is , between the bottom 131 and the reflecting member 113, of the printed circuit board 12 away at a first distance I ₁ in the first direction X _1, between each side facing each other at a first distance I ₁ space 41 extending in the horizontal direction are formed (hereinafter, referred to as "first heat radiating space 41") to, and, for each printed circuit board 12 to be separated in the second direction X ₂ at a second interval I _2, the second distance facing each other with the I ₂ Space 42 extending in the vertical direction is formed between the end portion (hereinafter, referred to as "second heat radiation space 42") to flow without staying.

Specifically, the heat conducting the reflecting member 113 and the printed circuit board 12, along the air flow in the formed by the first heat radiating space 41 in the longitudinal direction of the printed circuit board 12 extending in the horizontal direction (second parallel to the direction X ₂₎ Flowing. The airflows flowing along the longitudinal direction of the printed circuit board 12 are opposed to each other with the second distance I ₂ of each printed circuit board 12 that is spaced apart with the second distance I ₂ in the second direction X ₂ . When it reaches the part, it flows in the second heat radiating space 42 extending in the vertical direction while forming an updraft. Accordingly, heat can be efficiently radiated without heat remaining in the backlight unit 1.

  Further, since the first heat radiating space 41 and the second heat radiating space 42 are formed between the bottom 131 of the frame member 13 and the reflecting member 113, the side opposite to the side facing the bottom 131 of the reflecting member 113 is opposite. The airflow flowing through the first heat radiation space 41 and the second heat radiation space 42 does not flow into the region, that is, the region on the light irradiation surface side of the diffusion plate 3. Therefore, it is possible to efficiently dissipate heat while preventing foreign matters such as dust from flowing into the region on the light irradiation surface side of the diffusion plate 3 on the airflow.

Further, in the present embodiment, as shown in FIG. 8, the end portions of the printed circuit boards 12 that are separated from each other with the second interval I ₂ in the second direction X ₂ are opposed to each other with the second interval I _2. A drive signal input connector 12a, which is a drive signal input unit for inputting a drive signal to each LED chip 111a disposed on each printed circuit board 12, is provided at the end opposite to the printed circuit board 12. Accordingly, the drive signal input connector 12a is not provided in the first heat radiation space 41 and the second heat radiation space 42 for radiating the heat in the backlight unit 1, and thus the first heat radiation space 41 and the second heat radiation space. The airflow in 42 can be made smooth.

In the present embodiment, as shown in FIG. 8, among the plurality of printed circuit boards 12, at least some of the printed circuit boards 12 that form a pair with a second interval I ₂ in the second direction X ₂ are separated. each end to opposing, so as to be positioned on either side of parallel long side direction center portion in a second direction of H ₂ bottom 131 of the frame member, is disposed on the bottom 131. In the backlight unit 1 configured as described above, the second heat radiating space 42 is formed at the center in the long side direction of the bottom 131 of the frame member 13, and therefore, between the bottom 131 and the reflecting member 113. The existing warmed air flows through the central portion of the bottom portion 131 in the long side direction, and thereby, heat in the backlight unit 1 can be radiated.

For example, when the liquid crystal display device 100 is a display device such as a general-use television receiver and the backlight unit 1 is a backlight device provided in the display device, the shape and size corresponding to the liquid crystal panel 2 are obtained. The light emission intensity in the region corresponding to the center portion of the bottom portion 131 of the frame member 13 set to the height is increased. In such a case, heat tends to stay in the central portion of the bottom portion 131 of the frame member 13, but the second heat dissipation is performed in a region corresponding to the central portion in the long side direction parallel to the second direction X ₂ of the bottom portion 131. By forming the space 42, heat can be efficiently radiated.

Further, the shape of each printed circuit board 12 arranged and arranged on the bottom 131 of the frame member 13 is not limited to the above-described rectangular plate shape. 10 and 11 are diagrams showing the shape of the end faces of the respective opposite ends of each print board 12 to be separated in the second direction X ₂ at a second distance I _2.

For example, as shown in FIG. 10, each printed circuit board 12 to be separated in the second direction X ₂ at a second interval I _2, end faces of the end at a second distance I ₂ facing each other, each other It may be formed to be curved in a convex shape in the approaching direction. In this case, the minimum distance between the ends facing each other, and the second interval I _2. Thereby, since it can suppress that the airflow which flows through the 2nd thermal radiation space 42 turns into a turbulent flow, it can suppress more effectively that heat retains in the backlight unit 1, and can be carried out efficiently. It can dissipate heat.

Further, as shown in FIG. 11, each printed circuit board 12 to be separated in the second direction X ₂ at a second interval I _2, end faces of the end at a second distance I ₂ facing each other, printing toward the other side from the one side of the width direction parallel to the first direction X ₁ of the substrate 12 may be formed so as to be spaced apart from each other. In this case, the minimum distance between the ends facing each other, and the second interval I _2. Specifically, at each end, which are opposite to each other, the distance between one side of the first width direction parallel to the direction X ₁ of the printed circuit board 12, a second gap I _2. Parallel to the first direction X ₁ is vertical, as one widthwise side portion of the printed circuit board 12 is vertically upward side, when used in place of the backlight unit 1, flows through the second heat radiation space 42 Since the airflow flows from the other side in the width direction of the printed circuit board 12 to the one side, and from the wide side to the narrow side, the flow velocity is increased. Thereby, it is possible to more effectively suppress the heat from staying in the backlight unit 1 and to efficiently dissipate heat.

12, the backlight unit 60 is an exploded perspective view showing an enlarged configuration of each end portion opposed to each other for each printed board 12 to be separated in the second direction X ₂ at a second distance I ₂ . 13, the backlight unit 60 is a perspective view showing an enlarged configuration of each end portion opposed to each other of each print board 12 to be separated in the second direction X ₂ at a second distance I _2.

  The backlight unit 60 of the present embodiment is similar to the backlight unit 1 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. The backlight unit 60 is the same as the backlight unit 1 except that the configuration of the light emitting unit 60a is different from the configuration of the light emitting unit 11 described above.

  Each of the plurality of light emitting units 60a includes an LED chip 111a, a base 111 that supports the LED chip 111a, a lens 112, and a reflecting member 61.

  The reflection member 61 is provided around the base 111 on which the LED chip 111 a is supported, and reflects the light emitted from the lens 112 toward the liquid crystal panel 2 through the diffusion plate 3. The reflection member 61 has a polygonal shape, for example, a square shape, when viewed from the diffuser 3 side, that is, when viewed in plan in the direction of the optical axis S of the LED chip 111a.

  Moreover, when the reflection member 61 is planarly viewed in the optical axis S direction of the LED chip 111a, each side portion of the outer peripheral shape is continuous with the adjacent reflection member 61.

  The reflection member 61 is a base 611 having an opening 61a at the center, and an outer peripheral edge surrounding the base 611. The reflection member 61 is a flat plate formed so as to be inclined away from the printed circuit board 12 as the distance from the LED chip 111a increases. And an inclined portion 612. The reflecting member 61 constituted by the base 611 and the inclined portion 612 is provided in an inverted dome shape with the LED chip 111a as the center.

A characteristic configuration of the reflecting member 61 is that the inclined portion 612 is formed in a flat plate shape, and the outer peripheral edge of the inclined portion 612, that is, each side portion of the outer peripheral shape is adjacent to each other. It is connected with. In other words, on each printed circuit board 12 to be separated in the second direction X ₂ at a second interval I _2, each LED is arranged at a position closest to the ends facing each other at a second distance I ₂ The reflecting members 61 surrounding the chip 111a are formed so that the sides facing each other protrude from the printed circuit boards 12 and are connected to each other.

In the backlight unit 60 including such a reflecting member 61, the printed circuit boards 12 are arranged in the vicinity of the opposite ends of the printed circuit boards 12 that are spaced apart from each other with a second interval I ₂ in the second direction X ₂ . The raised portion of the reflecting member 61 that is raised apart is positioned. As a result, a space formed by the raised portions of the reflecting member 61 that are separated from the printed circuit boards 12, that is, a space formed between the inclined portions 612 that are connected to each other, is also included in the second heat radiation space 42.

  As a result, the second heat radiation space 42 becomes larger, so that the airflow in the second heat radiation space 42 can be made smooth. Therefore, it is possible to more effectively suppress heat from staying in the backlight unit 60, and to efficiently dissipate heat.

DESCRIPTION OF SYMBOLS 1,60 Backlight unit 2 Liquid crystal panel 3 Diffusion plate 11, 60a Light emission part 12 Printed circuit board 13 Frame member 41 1st thermal radiation space 42 2nd thermal radiation space 100 Liquid crystal display device 111 Base 111a LED chip 112 Lens 61,113 Reflection member

Claims (7)

A housing composed of a frame portion and a rectangular plate-shaped bottom portion surrounded by the frame portion;
A plurality of rectangular plate-like substrates arranged at the bottom with a first interval in the first direction and a second interval in a second direction orthogonal to the first direction;
A plurality of light emitting elements that emit light and are arranged at equal intervals in the second direction on each of the substrates;
A plurality of reflections provided on each substrate so as to surround each of the plurality of light emitting elements disposed on each substrate, extending toward both sides in the first direction of each substrate, and having a polygonal outer peripheral shape. A light emitting device comprising: a member;   End surfaces of the respective end portions of the respective substrates facing each other with a second interval are formed so as to be separated from each other in the direction from one side portion in the first direction of the substrate toward the other side portion. The light emitting device according to claim 1.   2. The light emitting device according to claim 1, wherein end surfaces of the respective end portions of the respective substrates facing each other with a second interval are curved in a convex shape in a direction of approaching each other.   The drive signal input part for inputting a drive signal to each light emitting element arrange | positioned on each board | substrate is provided in the 2nd direction one end part of each said board | substrate. The light emitting device according to any one of the above.   At least some of the substrates that are spaced apart from each other in the second direction to form a pair are arranged such that the end portions facing each other are located on both sides of the central portion in the second direction of the bottom portion. The light-emitting device according to claim 1, wherein the light-emitting device is a light-emitting device.   Each reflecting member surrounding each light emitting element disposed at a position closest to each end facing each other with a second interval between each substrate, each side facing each other protrudes away from each substrate, The light emitting device according to claim 1, wherein the light emitting device is formed so as to be continuous with each other. A display panel;
A light emitting device for irradiating light on the back of the display panel;
The display device according to claim 1, wherein the light-emitting device is the light-emitting device according to claim 1.

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