JP2013021136A - Light-emitting device and display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device, used for a backlight unit of a display device with a display panel, capable of irradiating the display panel with light so that brightness is uniform in the surface direction of the display panel and capable of achieving slimness.SOLUTION: A light-emitting device 11 installed on a backlight unit 1 includes: an LED chip 111a emitting light; a base 111 that is mounted on a printed board 12 and supports the LED chip 111a; a columnar lens 112 that is abutted on the LED chip 111a to cover the LED chip 111a and the base 111 and reflects or refracts incident light; and a mirror-finished reflection section 114. The mirror-finished reflection section 114 is abutted on the bottom face 112c of the lens 112 to mirror-reflect the light reaching a boundary surface with the bottom face 112c.

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 impact by not using mercury, but they are expensive in price, and until the blue LED is invented, the white LED is The absence of the light source and the strong directivity led to a delay in the use of the backlight unit as a light source. 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, Patent Document 1 discloses an inverted cone light emission including a light emitting element, a resin lens having an inverted conical recess provided so as to cover the light emitting element, and a reflecting plate provided around the resin lens. An element lamp is disclosed. Patent Document 2 discloses a light source unit that includes a light emitting element and a light guide reflector that guides light while reflecting light emitted from the light emitting element in a direction orthogonal to the optical axis.

JP 61-127186 A JP 2010-238420 A

  In the techniques disclosed in Patent Documents 1 and 2, light having strong directivity emitted from a light emitting element is diffused in a direction crossing the optical axis of the light emitting element, and light is irradiated onto the display panel in the surface direction. Can do.

  In recent years, there has been an increasing demand for thin display devices, and in direct light emitting devices provided in such thin display devices, light emitted from the light emitting elements intersects with the optical axis of the light emitting elements. Therefore, it is required to diffuse in a precise direction. However, the techniques disclosed in Patent Documents 1 and 2 cannot sufficiently satisfy the above requirements.

  For example, in the technique disclosed in Patent Document 1, the resin lens and the reflecting plate are provided on the substrate. The light reflected from the inside of the resin lens and emitted from the bottom surface opposite to the side facing the display panel is diffusely reflected by the substrate and is incident on the inside of the resin lens again. Since the light re-entering the resin lens in this manner is diffusely reflected by the substrate, the optical path is not accurately controlled, and the amount of light applied to the display panel becomes non-uniform.

  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, capable of emitting light to the display panel so that the luminance is uniform in the surface direction of the display panel. An apparatus and a display device including the light-emitting device are provided.

The present invention is a light emitting device for irradiating an irradiated body with light,
A light emitting element that emits light;
A columnar optical member that covers the light emitting element and is provided to face the irradiated body, and reflects or refracts light emitted from the light emitting element in a plurality of directions;
A specular reflection unit provided in contact with a bottom surface opposite to the side facing the irradiated body in the optical member, the specular surface reflecting specularly the light reaching the boundary surface between the bottom surface and the specular reflection unit A light emitting device comprising: a reflection portion.

In the light emitting device of the present invention, the optical member is formed in a columnar shape,
The light emitting element and the optical member are pre-aligned and formed so that the optical axis of the optical member coincides with the optical axis of the light emitting element,
The specular reflection part has a circular shape centered on the optical axis of the optical member.

  The light-emitting device of the present invention further includes a reflection member that is provided radially outward of the specular reflection portion and reflects light emitted from the optical member.

  In the light emitting device of the present invention, the specular reflection portion and the reflection member are partially overlapped when viewed from the optical axis direction of the optical member.

The light emitting device of the present invention includes a substrate that supports the light emitting element,
The specular reflection part is provided on the substrate.

  In the light emitting device of the present invention, the diffuse reflectance of the specular reflection portion is lower than the diffuse reflectance of the reflecting member.

  In the light emitting device of the present invention, the specular reflection portion is formed of silver or aluminum.

  In the light-emitting device of the present invention, the specular reflection portion is formed on the bottom surface of the optical member by aluminum vapor deposition.

The present invention also provides a display panel,
And a backlight unit including the light emitting device for irradiating light on the back surface of the display panel.

  According to the present invention, the light emitting device includes a light emitting element that emits light, and covers the light emitting element so as to face the irradiated object, and reflects or refracts light emitted from the light emitting element in a plurality of directions. A columnar optical member and a specular reflection part are provided. The specular reflection portion is provided in contact with the bottom surface of the optical member opposite to the side facing the irradiated body, and specularly reflects the light reaching the boundary surface with the bottom surface.

  In the light emitting device configured as described above, the light that is reflected inside the optical member and reaches the bottom surface opposite to the side facing the irradiated object is reflected at the boundary surface between the bottom surface of the optical member and the specular reflection portion. It is specularly reflected and travels inside the optical member. Since the light traveling in the optical member in this way is specularly reflected by the specular reflection portion, for example, the optical path is more accurate than light diffusely reflected and traveling in the optical member. It will be controlled.

  Therefore, the light emitting device accurately reflects and reflects the light emitted from the light emitting element and the light that is specularly reflected at the boundary surface between the bottom surface of the optical member and the specular reflection portion and travels inside the optical member. Since the light can be refracted, light can be irradiated onto the irradiated object so that the luminance is uniform in the surface direction of the irradiated object even when the display device is thinned.

  According to the invention, the optical member is formed in a columnar shape, and the light emitting element and the optical member are formed by being aligned in advance so that the optical axis of the optical member coincides with the optical axis of the light emitting element. And the specular reflection part is circular shape centering on the optical axis of an optical member. The light emitted from the light emitting element spreads in a circular shape around the optical axis by an optical member formed in a cylindrical shape. Since the specular reflection part has a circular shape centered on the optical axis of the optical member in accordance with the spread of light by the optical member, the light reaching the bottom surface of the optical member can be reliably specularly reflected.

  Moreover, according to this invention, a light-emitting device is further provided with the reflection member provided in the radial direction outer side of a specular reflection part. Since this reflecting member reflects the light emitted from the optical member, it is possible to suppress a decrease in the amount of light reaching the irradiated body.

  According to the invention, the specular reflection portion and the reflection member partially overlap each other when viewed from the optical axis direction of the optical member. As a result, it is possible to prevent a gap from being formed between the specular reflection part and the reflection member, so that the light emitted from the optical member can be reflected by the specular reflection part or the reflection member. It can suppress that the quantity of the light which reaches | attains an irradiation body falls.

  According to the invention, the light-emitting device is realized by further including a substrate that supports the light-emitting element, and the specular reflection portion is provided on the substrate.

  Moreover, according to this invention, the diffuse reflectance of a specular reflection part is lower than the diffuse reflectance of a reflecting member. This indicates that the specular reflectance of the specular reflection part is higher than the specular reflectance of the reflecting member. Therefore, the optical path of the light that is specularly reflected at the boundary surface between the bottom surface of the optical member and the specular reflection portion and travels inside the optical member is controlled with high accuracy.

  Moreover, according to this invention, a specular reflection part is formed with silver or aluminum. Thereby, the heat dissipation of the heat generated by the light emitting element can be enhanced.

  Moreover, according to this invention, a specular reflection part is formed in the bottom face of an optical member by aluminum vapor deposition. As a result, the specular reflection part can be formed without generating a gap between the bottom surface of the optical member, so that the light that has reached the bottom surface of the optical member can be reliably received at the boundary surface between the bottom surface and the specular reflection part. It can be specularly reflected.

  According to the invention, the display device includes the backlight unit including the light emitting device according to the invention, which can irradiate the display panel with light so that the luminance is uniform in the plane direction. Therefore, there is no occurrence of uneven brightness, and a high-quality image can be displayed on the display 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. 4 is a diagram for explaining a first assembly method of the light emitting device 11. FIG. It is a figure for demonstrating the 2nd assembly method of the light-emitting device. It is a figure for demonstrating the 3rd assembly method of the light-emitting device.

  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 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 that is an object to be irradiated and a backlight unit 1 including a light emitting device 11 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 included in the backlight unit 1. 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 thin film transistor (TFT), and liquid crystal is injected into a 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. A prism sheet 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 devices 11 that irradiate light to the liquid crystal panel 2, 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 includes a flat plate-like bottom portion 131 that faces the liquid crystal panel 2 at a predetermined interval, and a side wall portion 132 that is connected to the bottom portion 131 and rises from the bottom portion 131. Become. 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. A plurality of light emitting devices 11 are provided on the printed circuit board 12. The printed circuit board 12 is, for example, a substrate made of glass epoxy having conductive layers formed on both sides.

The plurality of light emitting devices 11 irradiate the liquid crystal panel 2 with light. In the present embodiment, a plurality of printed circuit boards 12 provided with a plurality of light emitting devices 11 are disposed so as to face the entire back surface 22 of the liquid crystal panel 2 through the diffusion plate 3 as a group. By arranging in parallel, the light emitting devices 11 are provided in a matrix. Each light emitting device 11 is formed in a square shape when viewed from a direction perpendicular to the bottom 131 of the frame member 13, and is defined such that the luminance of the surface of the diffusion plate 3 on the liquid crystal panel 2 side is 6000 cd / m ² . The length is, for example, 40 mm.

  Each of the plurality of light emitting devices 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, a reflecting member 113, and a specular reflecting portion 114. Including.

  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 device 11 is viewed from a direction perpendicular to the bottom 131 of the frame member 13. In the plurality of light emitting devices 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.

  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 base 111 by insert molding so as to cover the base 111 that supports 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 the surface facing the liquid crystal panel 2, is curved with a recess in the center, and the side surface 112b is formed in a substantially cylindrical shape parallel to the optical axis S of the LED chip 111a. A diameter L2 in a cross section orthogonal to the base is, for example, 10 mm, and is provided to extend outward with respect to the base 111. 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, and the center of the central portion 1121 (that is, the optical axis of the lens 112) is located on the optical axis S of the LED chip 111a. 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. Here, the outer peripheral edge portion of the central portion 1121 refers to a region around the entire circumference in the outer peripheral edge portion of the central portion 1121.

  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. For example, when the lens 112 is made of silicon resin, the refractive index of silicon resin is “1.43” and the refractive index of air is “1”, so sinφ = 1 / 1.43. . From this equation, the critical angle φ is 44.4 °, and the first curved portion 1122 is formed in a shape with an incident angle of 44.4 ° 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. Here, the outer peripheral edge portion of the first curved portion 1122 refers to a region around the entire circumference in the outer peripheral edge portion of the first curved portion 1122.

  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.

  In the present embodiment, the lens 112 is provided with a bottom surface 112 c on the side opposite to the side facing the liquid crystal panel 2 in the lens 112 in contact with the specular reflection unit 114.

  The specular reflector 114 is provided in contact with the bottom surface 112c of the lens 112, and specularly reflects light that has reached the bottom surface 112c. The specular reflection unit 114 has a specular reflectance of 98% or more with respect to visible light emitted from the LED chip 111a.

  In the light-emitting device 11 including the specular reflection unit 114, the light reflected inside the lens 112 and reaching the bottom surface 112 c can be specularly reflected at the boundary surface between the bottom surface 112 c and the specular reflection unit 114. The light that is specularly reflected at the boundary surface between the bottom surface 112 c and the specular reflection portion 114 travels inside the lens 112. Since the light traveling inside the lens 112 is specularly reflected by the specular reflection unit 114 in this way, for example, the optical path is more accurate than light that diffusely reflects and travels inside the lens 112. It will be well controlled. When light enters the diffusing member, the light diffuses, but does not necessarily emit as designed. On the other hand, since the light incident on the specular reflection unit 114 is regularly reflected, the light is emitted almost as designed. As a result, in the optical design, light can be made to proceed almost as designed, and the optical path is accurately controlled.

  Therefore, the light emitting device 11 causes the lens 112 to transmit the light emitted from the LED chip 111a and the light that is specularly reflected at the boundary surface between the bottom surface 112c of the lens 112 and the specular reflection unit 114 and travels inside the lens 112. Since the light can be reflected and refracted with high accuracy, even when used in the thin liquid crystal display device 100, the liquid crystal panel 2 can be irradiated with light so that the luminance is uniform in the surface direction. .

  The specular reflection portion 114 is formed by providing a silver or aluminum sheet on the printed circuit board 12. By forming the mirror reflection portion 114 from a metal such as silver or aluminum, the heat dissipation of the heat generated by the LED chip 111a can be enhanced. Moreover, the thickness of the specular reflection part 114 is 50 micrometers, for example.

  The specular reflection part 114 can also be formed by attaching a silver or aluminum sheet or performing aluminum vapor deposition on a base part 1131 of a reflection member 113 described later. In addition, you may form the reflective member 113 which has the specular reflection part 114 by shape | molding high-brightness PET (Polyethylene Terephthalate) etc. using the metal mold | die in which a part was mirror-finished. In this case, a part of the base portion 1131 becomes the specular reflection portion 114. In the case where the specular reflection part 114 is formed on the base part 1131 of the reflection member 113 by vapor deposition of aluminum, the reflection member 113 masking a part other than the region where the specular reflection part 114 is formed is placed in a vacuum container. Then, aluminum can be heated to evaporate to form the specular reflection portion 114 by aluminum deposition on the base portion 1131.

  Further, the specular reflection part 114 can also be formed as a thin metal layer on the bottom surface 112c of the lens 112 by aluminum vapor deposition. As a result, the specular reflection portion 114 can be formed without generating a gap between the bottom surface 112c of the lens 112, so that the light reaching the bottom surface 112c of the lens 112 can be transmitted between the bottom surface 112c and the specular reflection portion 114. The mirror surface can be reliably reflected at the boundary surface.

  In the present embodiment, the specular reflectance of the specular reflection unit 114 is 99%. The total reflectance of the specular reflection unit 114 is, for example, 98% to 100% with respect to visible light emitted from the LED chip 111a, and is 99% in the present embodiment.

  As specified in JIS H 0201: 1998, the specular reflectance is a reflectance in specular reflection, and can be measured by a conventionally known method based on JIS H 0201 137. The total reflectance is the sum of the specular reflectance and the diffuse reflectance, and can be measured according to JIS-K-7375.

  Further, the diffuse reflectance of the specular reflection portion 114 is lower than the diffuse reflectance of the reflecting member 113 described later. This indicates that the specular reflectivity of the specular reflection unit 114 is higher than the specular reflectivity of the reflection member 113. Therefore, light that is specularly reflected at the boundary surface between the bottom surface 112c of the lens 112 and the specular reflection unit 114 and travels inside the lens 112 has an optical path controlled accurately.

  Further, the specular reflection portion 114 has a circular shape centered on the optical axis of the lens 112 formed in a cylindrical shape when viewed from the optical axis S direction of the LED chip 111a. The outer diameter of the specular reflection unit 114 is set to be slightly larger than the diameter L2 of the lens 112. For example, the outer diameter of the lens 112 is set to 11 mm, whereas the diameter L2 of the lens 112 is 10 mm. The light emitted from the LED chip 111a spreads in a circular shape around the optical axis S by the lens 112 formed in a cylindrical shape. Since the specular reflection unit 114 has a circular shape centered on the optical axis of the lens 112 according to the spread of light by the lens 112, the light reaching the bottom surface 112c of the lens 112 can be specularly reflected. .

  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 112a facing the liquid crystal panel 2 is emitted in the direction of the arrow A1 toward the liquid crystal panel 2, and the first curved portion. The light that has reached 1122 is totally reflected and emitted from the side surface 112b in the direction of the arrow A2, and the light that has reached the second curved portion 1123 is refracted outward (in a direction away from the LED chip 111a) and is refracted. Toward the arrow A3.

  In addition, a part of the light reflected by the first curved portion 1122 of the lens 112 reaches the bottom surface 112c, but is specularly reflected at the boundary surface between the bottom surface 112c and the specular reflection portion 114 and travels inside the lens 112. The light is emitted in the direction of the arrow A4 from the side surface 112b.

  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.

  As a result, 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. Therefore, the distance H3 from the diffusion plate 3 to the printed board 12 can be reduced. Even in the small and thin liquid crystal display device 100, the liquid crystal panel 2 can be irradiated with light so that the luminance is uniform in the surface direction. A distance H3 from the diffusion plate 3 to the printed circuit board 12 is, for example, 6 mm.

  Returning to FIG. 2, the light emitting device 11 includes a reflecting member 113. The reflection member 113 is provided radially outward of the specular reflection portion 114 and reflects the light emitted from the lens 112 toward the liquid crystal panel 2. The reflection member 113 has a polygonal outer shape when viewed in plan in the direction of the optical axis S of the LED chip 111a, for example, a square shape. The reflection member 113 has a square flat plate-like base portion 1131 having an opening at the center and a length of one side of 38.8 mm, and surrounds the base portion 1131 so as to move away from the printed circuit board 12 as the distance from the LED chip 111a increases. And an inclined portion 1132 formed to be inclined. 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 shape when seen in a plan view 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 formed such that each side of the square shape when viewed in plan in the optical axis S direction of the LED chip 111a is parallel to the row direction or column direction of the plurality of LED chips 111a arranged in a matrix. The The base 1131 is formed along the printed circuit board 12 and has a square opening at the center when viewed in plan in the direction of the optical axis S. The length of one side of the square opening is approximately the same as the length L1 of one side of the base 111 that supports the LED chip 111a, and the base 111 is inserted through this opening.

  The inclined portion 1132 is connected to the outer peripheral edge of the base portion 1131 and extends in an inclined manner so as to be separated from the printed circuit board 12 as it goes outward (in a direction away from the LED chip 111a). An inclination angle θ1 between 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 optical axis S direction is, for example, 3.5 mm.

  The base portion 1131 and the inclined portion 1132 are made of high-brightness PET, 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 and the inclined part 1132 is, for example, 0.1 to 0.5 mm.

  The reflecting member 113 including the base portion 1131 and the inclined portion 1132 has a lower specular reflectance than the specular reflecting portion 114. That is, the diffuse reflectance of the reflecting member 113 is higher than the diffuse reflectance of the specular reflector 114. The specular reflectance of the reflecting member 113 is 80% to 98%, and the total reflectance is 94% to 98%.

  The reflection members 113 configured as described above and provided in each of the plurality of light emitting devices 11 are preferably formed integrally with each other. As a method of integrally molding the plurality of reflecting members 113, extrusion processing can be cited when the reflecting member 113 is made of high-brightness PET, and when the reflecting member 113 is made of aluminum. A press working can be mentioned. As described above, by integrally forming the reflecting members 113 respectively provided in the plurality of light emitting devices 11, it is possible to improve the accuracy of the arrangement positions of the plurality of light emitting devices 11 with respect to the printed circuit board 12, and Since the number of operations for attaching the reflecting member 113 can be reduced during the assembly operation, the efficiency of the assembly operation can be improved.

  Further, in the light emitting device 11 of the present embodiment, the specular reflection portion 114 and the base portion 1131 of the reflection member 113 are partially overlapped when viewed from the optical axis S direction of the LED chip 111a, that is, the optical axis direction of the lens 112. It is preferable to be provided. As a result, it is possible to prevent a gap from being formed between the specular reflection portion 114 and the base portion 1131 of the reflection member 113, so that the light emitted from the lens 112 can be transmitted to the specular reflection portion 114 or the reflection member 113. The light can be reflected by the base 1131 and the amount of light reaching the liquid crystal panel 2 can be suppressed from decreasing.

  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 is directed toward the liquid crystal panel 2 in the direction of the arrow A 1. The light reaching the first curved portion 1122 is 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 refracted outward and enters the liquid crystal panel 2. The light is emitted in the direction of the arrow A3.

  In addition, a part of the light reflected by the first curved portion 1122 of the lens 112 reaches the bottom surface 112c, but is specularly reflected at the boundary surface between the bottom surface 112c and the specular reflection portion 114 and travels inside the lens 112. The light is emitted in the direction of the arrow A4 from the side surface 112b.

  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 method for assembling the light emitting device 11 provided in the backlight unit 1 will be described. FIG. 7 is a view for explaining a first assembly method of the light emitting device 11. In the first assembly method, first, the lens 112 in which the LED chip 111 a supported by the base 111 is integrally molded is mounted on the printed circuit board 12. Specifically, solder is applied to the two connection terminal portions 121 of the conductive layer pattern included in the printed circuit board 12, and the two electrodes 111 c provided on the bottom surface of the base body 111 g are matched with the solder. As described above, the lens 112 in which the LED chip 111 a supported by the base 111 is integrally formed is placed on the printed circuit board 12. The printed circuit board 12 on which such a lens 112 is placed is sent to a reflow tank that irradiates infrared rays, the solder is heated to about 260 ° C., the base 111 and the printed circuit board 12 are soldered, and the lens 112 Is mounted on the printed circuit board 12.

  At this time, a gap is formed between the bottom surface 112c of the lens 112 and the printed circuit board 12, into which the circular sheet-like specular reflection portion 114 is inserted. Next, an opening 114a having a shape corresponding to the base 111 is formed at the center, and the specular reflection portion 114 having the slit-like cut-out portion 114b is opened at the bottom surface of the lens 112 so that the cut-out portion 114b is opened. The mirror reflection part 114 is placed on the printed circuit board 12 by being inserted between the printed circuit board 112 and the printed circuit board 12. Then, the reflecting member 113 in which the opening 113a having a shape corresponding to the lens 112 is formed is placed on the printed circuit board 12 on which the specular reflecting portion 114 is provided. In this way, the light emitting device 11 can be assembled.

  FIG. 8 is a diagram for explaining a second assembling method of the light emitting device 11. In the second assembly method, first, the LED chip 111 a supported by the base 111 is mounted on the printed circuit board 12. Specifically, solder is applied to the two connection terminal portions 121 of the conductive layer pattern included in the printed circuit board 12, and the two electrodes 111 c provided on the bottom surface of the base body 111 g are matched with the solder. As described above, the LED chip 111 a supported by the base 111 is placed on the printed circuit board 12. The printed circuit board 12 on which the LED chip 111a supported by the base 111 is placed is sent to a reflow tank that irradiates infrared rays, and the solder is heated to about 260 ° C. so that the base 111 and the printed circuit board 12 are connected to each other. The LED chip 111 a that is soldered and supported by the base 111 is mounted on the printed circuit board 12.

  Next, the specular reflection part 114 in which the opening 114a having a shape corresponding to the base 111 is formed is placed on the printed circuit board 12 so that the base 111 and the LED chip 111a are exposed. Next, the bottom surface 112c of the lens 112 is brought into contact with the specular reflection portion 114 so as to cover the LED chip 111a with the lens 112 having the recess 112d having a shape corresponding to the base 111 and the LED chip 111a. Attach to 111. Then, the reflecting member 113 in which the opening 113a having a shape corresponding to the lens 112 is formed is placed on the printed circuit board 12 on which the specular reflecting portion 114 is provided. In this way, the light emitting device 11 can be assembled. The diameter of the opening 113a is set to 10.5 mm while the diameter L2 of the lens 112 is 10 mm.

  FIG. 9 is a diagram for explaining a third assembling method of the light emitting device 11. In the third assembling method, first, the lens 112 in which the LED chip 111 a supported by the base 111 is integrally molded is mounted on the printed circuit board 12. At this time, a gap is formed between the bottom surface 112c of the lens 112 and the printed circuit board 12, into which the specular reflection unit 114 is inserted. Next, the reflecting member 113 in which the opening 113 a having a shape corresponding to the lens 112 is formed is placed on the printed circuit board 12. Then, an opening 114a having a shape corresponding to the base 111 is formed in the center, and the specular reflection portion 114 in which the slit-like cut portion 114b is formed opens the cut portion 114b, so that the bottom surface 112c of the lens 112 is opened. And the specular reflection part 114 is placed on the printed circuit board 12. In this way, the light emitting device 11 can be assembled.

DESCRIPTION OF SYMBOLS 1 Backlight unit 2 Liquid crystal panel 3 Diffusion plate 11 Light-emitting device 12 Printed circuit board 13 Frame member 100 Liquid crystal display device 111 Base 111a LED chip 112 Lens 113 Reflective member 114 Specular reflection part

Claims (9)

A light emitting device for irradiating an irradiated object with light,
A light emitting element that emits light;
A columnar optical member that covers the light emitting element and is provided to face the irradiated body, and reflects or refracts light emitted from the light emitting element in a plurality of directions;
A specular reflection unit provided in contact with a bottom surface opposite to the side facing the irradiated body in the optical member, the specular surface reflecting specularly the light reaching the boundary surface between the bottom surface and the specular reflection unit A light emitting device comprising: a reflection portion; The optical member is formed in a cylindrical shape,
The light emitting element and the optical member are pre-aligned and formed so that the optical axis of the optical member coincides with the optical axis of the light emitting element,
The light-emitting device according to claim 1, wherein the specular reflection portion has a circular shape centering on an optical axis of the optical member.   The light emitting device according to claim 2, further comprising a reflecting member that is provided radially outward of the specular reflection portion and reflects light emitted from the optical member.   4. The light emitting device according to claim 3, wherein the specular reflection portion and the reflection member partially overlap each other when viewed from the optical axis direction of the optical member. A substrate for supporting the light emitting element;
The light-emitting device according to claim 1, wherein the specular reflection unit is provided on the substrate.   The light-emitting device according to claim 3, wherein a diffuse reflectance of the specular reflection portion is lower than a diffuse reflectance of the reflective member.   The light-emitting device according to claim 1, wherein the specular reflection part is made of silver or aluminum.   The light-emitting device according to claim 1, wherein the specular reflection unit is formed on the bottom surface of the optical member by aluminum vapor deposition. A display panel;
A backlight unit including a light emitting device for irradiating light on the back of the display panel;
The said light-emitting device is a light-emitting device as described in any one of Claims 1-8, The display apparatus characterized by the above-mentioned.