JP2011134485A - Light-emitting device - Google Patents

Abstract

Provided is a light-emitting device in which a light source that emits light not only from the side but also from above is housed in a housing hole extending in the thickness direction of a light guide plate without impairing light emission efficiency.
A light source having an element mounting substrate, an LED element mounted on the element mounting substrate by flip chip connection, and a sealing portion for sealing the LED element on the element mounting substrate. And the light guide plate 1 having the accommodation hole 2 in which the light source 3 is accommodated, and the accommodation hole 2 extends from the one surface 11 to the other surface 12 side of the light guide plate 1, Among these, the light incident range from the light source 3 is parallel to the thickness direction of the light guide plate 1, and the light source 3 is accommodated in the accommodation hole 2 so that the element mounting substrate 33 is on the other surface 12 side of the light guide plate 1. The light is emitted to the one surface 11 side of the light guide plate 1 of the housing hole 2 and the inner surface 21 side of the housing hole 2, and the optical axis is parallel to the thickness direction of the light guide plate 1. 21 is a solid angle with respect to the center of the upper surface 34a of the light guide plate 1 in the light source 3. It is .44steradian or more.
[Selection] Figure 1

Description

  The present invention relates to a light-emitting device that causes light from a light source having LED elements mounted by flip-chip connection to enter a light guide plate.

  A light source in which an LED element on an element mounting substrate is sealed with an inorganic material such as glass is known (for example, see Patent Document 1). In the light source described in Patent Document 1, a plurality of LED elements are mounted on an element mounting substrate by flip chip connection, and each LED element is collectively sealed with glass by performing hot press processing of glass. Yes. This light source has a cubic shape, and light is emitted from the upper surface and side surfaces. The optical axis is perpendicular to the element mounting board.

  Further, a light emitting device using a light guide plate is known in which a plurality of cylindrical hole-shaped or concave incident portions are arranged in parallel on the back surface portion in the vicinity of at least one side surface portion of the light guide plate (for example, , See Patent Document 2). In this light emitting device, the incident portion is formed in the thickness direction of the light guide plate, and a planar emission type light source that emits light to the side is used. Specifically, the light source has concentric inclined surface portions on the inner surface and the outer surface on the top, totally reflects light from the semiconductor light emitting element at the inclined surface portions on the inner surface, and breaks the critical angle at the inclined surface portion on the outer surface. Radiate in all directions.

International Publication No. 2004/82036 JP 2005-276491 A

  However, in the light emitting device described in Patent Document 2, it is necessary to select a light source that emits light in a planar manner, and a light source that emits light from the upper surface as described in Patent Document 1 is simply adopted as the light source. As a result, the luminous efficiency is lowered, resulting in a result contrary to the object of the invention described in Patent Document 2.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a light source that emits light not only from the side but also from above without impairing light emission efficiency, in the thickness direction of the light guide plate. An object of the present invention is to provide a light emitting device accommodated in an accommodation hole extending to the front.

  In order to achieve the above object, in the present invention, an element mounting substrate, an LED element mounted on the element mounting substrate by flip chip connection, a sealing portion for sealing the LED element on the element mounting substrate, And a light guide plate having an accommodation hole in which the light source is accommodated, the accommodation hole extending from one surface of the light guide plate to the other surface side, and a range in which light is incident from the light source on the inner surface Is parallel to the thickness direction of the light guide plate, and the light source is housed in the housing hole so that the element mounting substrate is on the other surface side of the light guide plate, and one surface of the light guide plate in the housing hole Side and the inner surface side of the receiving hole, the optical axis is parallel to the thickness direction of the light guide plate, and the inner surface of the receiving hole with respect to the center of the upper surface of the light source Light-emitting device whose solid angle is 4.44 steradian or more It is provided.

  In the light emitting device, it is preferable that the accommodation hole is formed so as to penetrate the light guide plate.

  The light-emitting device preferably includes a mounting substrate provided on one surface side of the light guide plate and on which the light source is mounted.

  Moreover, the said light-emitting device WHEREIN: The said sealing part is good also as heat-fusion glass.

  In the light emitting device, the light source may have a rectangular parallelepiped shape.

  In the light emitting device, the sealing portion may be dispersed with a phosphor that converts the wavelength of light emitted from the LED element.

  The light emitting device may further include a reflecting plate that is provided on the other surface side of the light guide plate and closes the accommodation hole.

  According to the present invention, a light source that emits light not only from the side but also from above can be accommodated in the accommodation hole extending in the thickness direction of the light guide plate without impairing the light emission efficiency.

FIG. 1 is an external perspective view of a light-emitting device showing a first embodiment of the present invention. FIG. 2 is a cross-sectional view of the light emitting device. FIG. 3 is an explanatory diagram when the light source is manufactured. FIG. 4 is an explanatory diagram when the light source is manufactured. FIG. 5 is a plan view of an intermediate body to which light sources are connected. FIG. 6 is an explanatory diagram when the LED element of the light source is wire-bonded. FIG. 7 is a cross-sectional view of a light emitting device showing a modification. FIG. 8 is a cross-sectional view of a light emitting device showing a modification. FIG. 9 is a cross-sectional view of a light emitting device showing a modification. FIG. 10 is a cross-sectional view of a light emitting device showing a modification. FIG. 11 is a cross-sectional view of a light emitting device showing a modification. FIG. 12 is a bottom view of a light emitting device showing a modification. FIG. 13 is a cross-sectional view of a light emitting device showing a modification. FIG. 14 is a cross-sectional view of a light emitting device showing a modification. FIG. 15 is a cross-sectional view of the light emitting device showing the second embodiment. FIG. 16 is a plan view of the light emitting device. FIG. 17 is a cross-sectional view of a light emitting device showing a modification. FIG. 18 is a plan view of a light emitting device showing a modification. FIG. 19 is a cross-sectional view of a light emitting device showing a modification.

  1 to 5 show a first embodiment of the present invention, and FIG. 1 is an external perspective view of a light emitting device.

  As shown in FIG. 1, the light emitting device 1 is electrically connected to the light guide plate 1, the accommodation hole 2 formed in the light guide plate 1, the light source 3 accommodated in the accommodation hole 2, and the light source 3. And a mounting substrate 4. The light guide plate 1 is made of a material that is transparent to the light emitted from the light source 3, and the light emitted from the light source 3 in the accommodation hole 2 is incident thereon. In the present embodiment, the light guide plate 1 is formed in a flat plate shape having a constant thickness throughout. In the present embodiment, the thickness of the light guide plate 1 is 3 mm. The material of the light guide plate 1 is arbitrary as long as it is transparent with respect to the light of the light source 3, but may be acrylic resin, for example. Here, in this specification, one surface of the light guide plate 1 will be described as the upper surface 11 and the other surface will be described as the lower surface 12.

  The accommodation hole 2 extends from the upper surface 11 to the lower surface 12 side of the light guide plate 1, and is parallel to the thickness direction of the light guide plate 1 with respect to the range where light from the light source 3 enters the inner surface 21. In the present embodiment, the accommodation hole 2 has a circular shape with a diameter of 2 mm in plan view, is formed through the light guide plate 1, and has the same cross section in the upper and lower sides. As will be described later, light is emitted upward and laterally from the light source 3, and light from the light source 3 enters the entire range of the inner surface 21 of the accommodation hole 2. In the present embodiment, the plurality of receiving holes 2 are arranged at equal intervals along one side of the light guide plate 1.

FIG. 2 is a cross-sectional view of the light emitting device.
As shown in FIG. 2, the light source 3 includes an LED element 32 made of a flip-chip type GaN-based semiconductor material, an element mounting substrate 33 on which the LED element 32 is mounted, an LED element 32 and an element mounting substrate 33. And a glass sealing portion 34 as an inorganic sealing portion to be bonded. The element mounting substrate 33 is made of a polycrystalline sintered material of alumina (Al ₂ O ₃ ) and has a thickness of 0.25 mm and a 1.0 mm square. The LED element 32 is 100 μm thick and 346 μm square.

The glass sealing portion 34 covers the LED element 2 mounting surface side of the element mounting substrate 33 together with the LED element 32, and has a thickness of 0.6 mm. It has an upper surface 34a parallel to the element mounting substrate 33, and a side surface 34b extending downward from the outer edge of the upper surface 34a and perpendicular to the element mounting substrate 3. The glass sealing part 34 can be made of, for example, ZnO—B ₂ O ₃ —SiO ₂ glass, and the refractive index in this case is 1.7. Further, this glass is a heat-sealed glass fused to the element mounting substrate 33 by heating, and is different from a glass formed by utilizing a sol-gel reaction. The composition and refractive index of the glass are not limited to these. Further, the glass sealing portion 34 includes a phosphor that converts the wavelength of light emitted from the LED element 2. As the phosphor, for example, a YAG (Yttrium Aluminum Garnet) phosphor, a silicate phosphor, or a mixture of YAG and a silicate phosphor at a predetermined ratio can be used. In this embodiment, a blue LED element is used. White light is obtained from 32 and yellow phosphor. In addition, you may make it obtain white light by the combination of the LED element which emits ultraviolet light, and a blue fluorescent substance, a green fluorescent substance, and a red fluorescent substance. Further, the phosphor may be applied to the surface of the glass sealing portion 34 without including the phosphor in the glass sealing portion 34, or the phosphor may not be used.

  The light source 3 emits blue light from the LED element 32 when a voltage is applied to the LED element 32. The blue light emitted from the LED element 32 is partly converted to yellow by the phosphor, and then emitted to the outside through the upper surface 34 a or the side surface 34 b of the glass sealing portion 34. The light source 3 is perpendicular to the element mounting substrate 33, and an axis passing through the center of the upper surface 34a is an optical axis. In the light source 3, the light intensity on the optical axis does not become the maximum, but the light distribution characteristic has the maximum light intensity in the direction inclined by about 30 ° to 45 ° with respect to the optical axis. This light source 3 is manufactured through the following steps.

  First, a glass component oxide powder is heated to 1200 ° C. and stirred in a molten state. And after solidifying glass, it slices so that it may correspond to the thickness of the glass sealing part 34, and the glass 35 before sealing is processed into plate shape. Then, the recessed part 35a corresponding to each LED element 32 is formed in the glass 35 before sealing so that it may mention later.

  On the other hand, a circuit pattern is formed on the flat element mounting substrate 33. For example, the circuit pattern is obtained by screen-printing a metal paste and heat-treating the element mounting substrate 33 at a predetermined temperature (for example, 1000 ° C. or higher) to burn the metal on the element mounting substrate 33, It can be formed by plating. Thereafter, the plurality of LED elements 32 are mounted on the element mounting substrate 33 by flip chip connection at equal intervals in the vertical and horizontal directions. In addition, the circuit pattern of the element mounting substrate 33 may be only formed by heat treatment of a metal paste, or may be formed by other methods such as a metal plating after metal sputtering.

Then, as shown in FIG. 3, the element mounting substrate 33 on which each LED element 32 is mounted is set on the lower mold 91, and the upper mold 92 is disposed to face the mounting surface of the element mounting substrate 33. The pre-sealing glass 35 is disposed between the mounting substrate 33 and the upper mold 92 so that the mounting area of each LED element 32 is covered. Thereafter, as shown in FIG. 4, the lower mold 91 and the upper mold 92 are pressurized, and hot pressing of a glass material softened by heating in a nitrogen atmosphere is performed. The processing conditions at this time can be arbitrarily changed according to the temperature, pressure and the like of the glass. For example, the temperature of the glass is 600 ° C., and the pressure of the glass is 25 kgf / cm ^2. It can be. Of course, the glass to be set may have a planar shape in which no recess is formed.

  Through the above steps, an intermediate body 36 as shown in FIG. 5 in a state where the plurality of light emitting devices 1 are connected in the vertical direction and the horizontal direction is manufactured. Thereafter, the element mounting substrate 33 integrated with the glass sealing portion 34 is set in a dicing apparatus, and the glass sealing portion 34 and the element mounting substrate 33 are diced by the dicing blade so as to be divided into the LED elements 32. Thus, the light source 3 is completed.

  As shown in FIG. 2, the mounting substrate 4 is based on aluminum and is provided along the lower surface 12 of the light guide 1. In the present embodiment, the mounting substrate 4 is provided so as to close each accommodation hole 2. The mounting substrate 4 includes a substrate body 41 made of aluminum, an insulating layer 42 provided on the substrate body 41, a circuit pattern 43 provided on the insulating layer 42, and a white resist layer provided on the circuit pattern 43. 44.

Next, the relationship between the light source 3 and the accommodation hole 2 will be described.
The light source 3 of 1.0 mm square in plan view is mounted at the center of the receiving hole 2 having a diameter of 2 mm in plan view. The light source 3 is housed in the housing hole 2 so that the element mounting substrate 33 is on the lower surface 12 side of the light guide plate 1, and the optical axis is parallel to the thickness direction of the light guide plate 1. Further, the light source 3 having a height of 0.85 mm is mounted on the mounting substrate 4 via the solder 31. Thereby, the light source 3 is arrange | positioned by the height of 0.85 mm from the lower end of the accommodation hole 2 whose vertical length is 3 mm. As a result, the solid angle of the inner surface 21 of the receiving hole 2 with respect to the center of the upper surface 34a of the light source 3 of the inner surface 21 of the receiving hole 2 is 90% (5.65 steradian) with respect to 2πsteradian of the upper hemisphere. The ratio of the solid angle of the inner surface 21 of the receiving hole 2 with respect to the center of the side surface 34b (target πsteradian on the upper side of the hemisphere of the side surface) is larger than the upper surface 34a. It can be said that the ratio is at least 90% or more. Further, the direction in which the light intensity of the light source 3 is maximum is about 45 °, and the inner surface 21 exists in this direction.

  According to the light emitting device 1 configured as described above, at least 90% or more of the light emitted from the light source 3 enters the inner surface 21 of the light guide plate 1. Since the light is refracted in a direction approaching parallel to the upper surface 11 and the lower surface 12 of the light guide plate 1 at the time of incidence, most of the incident light can be used as propagation light. Here, the refractive index of the light guide plate 1 is preferably 1.41 or more because the critical angle can be 45 ° or less. That is, even light that is incident on the inner surface 21 of the receiving hole 2 substantially in parallel (approximately 90 ° with respect to the normal direction of the inner surface 21) is refracted and becomes light within 45 ° with respect to the normal direction of the inner surface 21. Since the upper surface 11 and the lower surface 12 of the light guide plate 1 are 90 ° with respect to the normal direction of the inner surface 21 of the receiving hole 2, the condition of total reflection is satisfied on the upper surface 11 and the lower surface 12 with respect to the incident light. As a result, all the light incident from the inner surface 21 of the accommodation hole 2 becomes propagation light. Thus, special optics that controls the light emitted upward from the light source 3 to be in the in-plane direction of the light guide plate 1 even though the optical axis of the light source 3 is in the thickness direction of the light guide plate 1. Without using the automatic control unit for the light source 3 and the light guide plate 1, it is possible to obtain a function and effect that is contrary to technical common sense that light can be accurately incident into the light guide plate 1 to be propagated light of the light guide plate 1. be able to. Therefore, the number of parts can be reduced by omitting the optical control unit, and the light emitting device 1 can be easily and easily manufactured.

  Note that the ratio of the solid angle on the inner surface 21 of the receiving hole 2 with respect to the center of the upper surface 34a of the light source 3 is not necessarily 90% or more with respect to 2πsteradian of the upper hemisphere, but it is 70% (for optical efficiency). 4.44 steradian) or more is desirable. Furthermore, it is desirable that the inner surface 21 of the receiving hole 2 exists in the direction in which the light intensity of the light source 3 is maximized. The inner surface 21 of the accommodation hole 2 is preferably a smooth surface that is perpendicular to the light guide plate 1 and not rough, but the refractive index of the light guide plate 1 or the light source 3 to the inner surface 21 of the accommodation hole 2. In relation to the incident angle, a slight inclination and a roughness in the direction of 90 ° with respect to the thickness direction of the light guide plate 1 are allowed because they do not significantly reduce the efficiency.

  Moreover, according to this embodiment, since the LED element 32 of the light source 3 is mounted by flip chip connection, the size of the light source 3 in a plan view can be reduced, and the diameter of the accommodation hole 2 can also be reduced. . This makes it possible to mount the light source 3 with the optical axis in the thickness direction without increasing the thickness of the light guide plate 1. For example, as shown in FIG. 6, when the LED element 32 is mounted by wire bonding connection, the first distance a for the wire loop, the element mounting substrate 33, and the wire 39 are arranged outside the LED element 32. An extra second distance b for connection is required. The first distance a is, for example, 0.3 to 0.5 mm, and the second distance b is, for example, 0.2 to 0.5 mm. Therefore, in the case of wire bonding, the element mounting substrate 33 is the same as that of the first embodiment. It is necessary to make it larger than 0.0 mm square. For example, when the size of the element mounting substrate 33 is 2.5 mm square, the diameter of the accommodation hole 2 of the light guide plate 1 needs to be increased to, for example, 5 mm. If the light emitting device 1 is manufactured in such a size, even if the LED elements 32 to be mounted are the same, the ratio of the solid angle of the inner surface 21 with respect to the central portion of the upper surface 34a of the light source 3 is 75. %. In addition, when the height of the light source 3 is not changed and the size in plan view is reduced, the light distribution in the lateral direction is relatively increased. In addition, when the phosphor is dispersed in the sealing material, if the dimension in the planar direction is smaller than the height of the sealing material, the difference in chromaticity of light between the upward direction and the lateral direction tends to become noticeable. Even if this difference occurs, light can be mixed in the light guide plate 1.

  Moreover, according to this embodiment, since it is not necessary to optically process the upper surface 34a and the side surface 34b of the light source 3, manufacture of the light source 3 is also easy and easy. In the case of the light emitting device 1, a light source 3 having a light distribution that does not have the maximum light intensity on the optical axis is preferable, and a simple accommodation hole 2 may be formed without processing the cube-shaped light source 3. Therefore, it is extremely advantageous for practical use.

  In the embodiment, the light source 3 in which the LED element 32 is sealed with glass is shown. However, the LED element 32 is flip-chip connected to the element mounting substrate 33, and the sealing material is framed in a plan view. If the light source 3 has no portion, the sealing material may be changed.

  The heat-sealed glass-sealed LED is easy to form in the height direction, has the same thermal expansion coefficient as the element mounting substrate, and has a large bonding force between both members. Although it can be reduced, it is desirable to widen the light distribution in the lateral direction. For example, as shown in FIG. 7, the LED element 32 is sealed with a sealing sealing portion 37 such as silicon resin or epoxy resin. Also good. In the light source 3 of FIG. 7, the resin sealing portion 37 is formed in a hemispherical shape on the element mounting substrate 33.

For example, as shown in FIG. 8, the LED element 32 may be sealed with an inorganic paste 38 having a predetermined thickness. As the inorganic paste 38, for example, a material such as SiO ₂ , Al ₂ O ₃ , or TiO ₂ can be used.

  Moreover, in the said embodiment, although what showed the upper direction of the accommodation hole 2 was shown, the member which plugs the upper direction of the accommodation hole 2 is provided, and the secondary light by reflection also becomes the propagation light of the light-guide plate 1. You may plan. For example, as shown in FIG. 9, the light traveling upward from the accommodation hole 2 can be incident on the inner surface 21 of the light guide plate 1 by closing the upper portion of the accommodation hole 2 with a reflection plate 51. If the reflecting surface of the reflecting plate 51 is made of a material having a relatively high surface reflectance, for example, aluminum, the specular reflection can be efficiently used. When the reflecting surface is aluminum, for example, the reflecting plate 51 itself may be an aluminum plate, or an aluminum foil may be attached to the reflecting surface of the reflecting plate 51. In this case, direct light from the light source 3 to the outside can be blocked, which is effective when preventing direct light emission.

  Further, for example, as shown in FIG. 10, the reflection plate 52 may mainly use diffuse reflection. In this case, a white diffusion sheet can be used on the inner surface of the reflecting plate 52. In the embodiment, since the incident angle of light incident on the reflecting plate 52 is relatively small, it is preferable to use diffuse reflection rather than specular reflection.

  Furthermore, for example, as shown in FIG. 11, a part of light may be transmitted from the reflection plate 53. As a result, only the amount of light necessary for external radiation is extracted to the outside, and the other light enters the optical plate 1.

  Moreover, in the said embodiment, although it does not process in particular on both surfaces of the light-guide plate 1, of course, you may perform arbitrary processes as needed. For example, as shown in FIGS. 12 and 13, at least one surface of the light guide plate 1 may be subjected to reflection processing. 12 and 13, a plurality of circular reflection portions 206 are formed on the lower surface 12 so that light in the light guide plate 1 is reflected by the reflection portion 206 and extracted from the upper surface 11. . In this case, as shown in FIG. 12 and FIG. 13, if each reflecting portion 206 is made smaller and further away from the light source 3, the amount of light extracted from the upper surface 11 is made uniform regardless of the distance from the light source 3. be able to.

  The reflection portion 206 can be formed by screen printing, ink jet printing, laser processing, thermal transfer using a mold, or the like. In particular, in the case of inkjet printing, laser processing, or the like, a plate used in screen printing or the like is not necessary, and for example, the reflective portion 206 can be processed according to the light emission characteristics of the light emitting device 200 that is actually manufactured. Furthermore, in the case of inkjet printing, by arranging the nozzles on the entire surface of the light guide plate 1, there is an advantage that a wide range of processing can be performed at the same time and workability is excellent.

  In the embodiment, the light guide plate 1 is formed in a flat plate shape. However, the shape of the light guide plate 1 may be appropriately changed as long as it guides the light incident from the accommodation hole 2. Of course. For example, as illustrated in FIG. 14, the lower surface 312 may be curved so as to be closer to the upper surface 311 as the distance from the light source 3 increases. The light emitting device 300 can also make the light extracted from the upper surface 311 uniform. Moreover, since the light source 3 is small without an optical system, a large number of light sources 3 can be densely arranged to provide a high-intensity light guide plate 301. On the other hand, even when the light sources 3 are arranged with a relatively large interval, light is emitted in a surface direction of 360 °, so that a decrease in luminance between the light sources 3 can be prevented. Furthermore, since the space | interval of the adjacent accommodation hole 2 becomes wide and the area | region of the main-body part of the light-guide plate 300 becomes large, it is easy to transmit the light radiate | emitted on the left side of the light of the light source 3 in FIG. Can do.

15 and 16 show a second embodiment of the present invention, and FIG. 15 is a cross-sectional view of the light emitting device.
As shown in FIG. 15, the light emitting device 400 is electrically connected to the light guide plate 401, the accommodation hole 402 formed in the light guide plate 401, the light source 403 accommodated in the accommodation hole 402, and the light source 403. A mounting substrate 442. The light guide plate 401 is made of a material that is transparent to the light emitted from the light source 3, and the light emitted from the light source 403 in the accommodation hole 402 is incident thereon. In the present embodiment, the light guide plate 401 is formed in a flat plate shape having a constant thickness throughout. In the present embodiment, the thickness of the light guide plate 401 is 5 mm.

  The accommodation hole 402 extends from the upper surface 411 to the lower surface 412 side of the light guide plate 401, and is parallel to the thickness direction of the light guide plate 401 in the range where the light from the light source 403 is incident on the inner surface 421. In the present embodiment, the accommodation hole 402 has an oval shape including a semicircular portion having a radius of 0.75 mm and a straight portion having a length of 3.0 mm in plan view, and is formed through the light guide plate 401. It has the same cross section.

The light source 403 includes a plurality of LED elements 32 made of a flip-chip type GaN-based semiconductor material, an element mounting substrate 433 on which the LED elements 32 are mounted, and the LED elements 32 are sealed and bonded to the element mounting substrate 433. A glass sealing portion 434 as an inorganic sealing portion, and a heat dissipation pattern 431 formed on the back surface of the element mounting substrate 433. The element mounting substrate 433 is made of a polycrystalline sintered material of alumina (Al ₂ O ₃ ), and is formed in a rectangular shape having a thickness of 0.25 mm, a long side of 2.8 mm, and a short side of 0.75 mm. .

  The glass sealing portion 434 covers the LED element 32 mounting surface side of the element mounting substrate 433 together with the LED element 32, and has a thickness of 0.7 mm. The glass sealing portion 434 has an upper surface 434a parallel to the element mounting substrate 433, and a side surface 434b extending downward from the outer edge of the upper surface 434a and perpendicular to the element mounting substrate 433.

  The mounting substrate 442 is based on polyimide and is provided along the lower surface 412 of the light guide plate 401. In the present embodiment, a white reflective sheet 454 is provided between the lower surface 412 of the light guide plate 401 and the mounting substrate 404. Furthermore, in the present embodiment, a white reflective sheet 455 is also provided on the upper surface 411 of the light guide plate 401. Further, a connection hole 404 a is formed below the light source 403 in the mounting substrate 404, and the heat dissipation pattern 431 and the aluminum frame 441 are connected by the solder 31 through the hole 404 a. The aluminum frame 441 is entirely formed on the lower surface 412 side of the light guide plate 401. The mounting substrate 442 may be based on aluminum or copper. In this case, the mounting substrate 442 may be soldered to the heat radiation pattern 431 via an insulating layer. Furthermore, the insulating layer corresponding to the heat radiation pattern 431 is not formed, and aluminum or copper of the mounting substrate 442 is soldered to the heat radiation pattern 431 without using an insulating layer so that the heat radiation pattern is high. It is good.

Next, the relationship between the light source 403 and the accommodation hole 402 will be described.
The light source 403 is mounted such that its center of gravity overlaps the center of the accommodation hole 402 in plan view. The light source 3 having a height of 0.95 mm is mounted on the mounting substrate 442 via the solder 31. Accordingly, the light source 403 is disposed at a height of 0.95 mm from the lower end of the accommodation hole 402 having a vertical length of 5 mm. As a result, the ratio of the solid angle of the inner surface 421 of the accommodation hole 402 to the center (center of gravity) of the upper surface 434a of the light source 403 is less than 90%. And since the solid angle with respect to the center part of the side surface 434b becomes larger than the upper surface 434a, when it sees as the light source 403 whole, a solid angle is at least 90% or more.

FIG. 16 is a plan view of the light emitting device.
As shown in FIG. 16, the aluminum frame 441 has a pair of horizontal flange portions 441a and a pair of vertical flange portions 441b extending upward at the ends, and the light guide plate 401 (see FIG. 16) inside each flange portion 441a, 441b. 16 (not shown in FIG. 16), a white reflective sheet 455 and the like are disposed. In the present embodiment, a plurality of horizontally long light sources 403 are arranged in a line in the horizontal direction. Further, the accommodation hole 402 of the light guide plate 401 is formed in a horizontally long shape corresponding to the light source 403, and is formed side by side in the horizontal direction at the center of the light guide plate 401 in the vertical direction.

  According to the light emitting device 400 configured as described above, at least 90% or more of the light emitted from the light source 403 is incident on the inner surface 421 of the light guide plate 1. Since the light is refracted in a direction approaching parallel to the upper surface 411 and the lower surface 412 of the light guide plate 401 at the time of incidence, most of the incident light can be used as propagation light. As a result, special optics that controls the light emitted upward from the light source 403 to be in the in-plane direction of the light guide plate 401 even though the optical axis of the light source 403 is in the thickness direction of the light guide plate 401. Without using the automatic control unit for the light source 403 and the light guide plate 401, it is possible to obtain a function and effect contrary to the common general knowledge that light can be accurately incident into the light guide plate 401 to be propagated light of the light guide plate 401. be able to. Therefore, the number of parts can be reduced by omitting the optical control unit, and the light emitting device 401 can be manufactured easily and easily. Further, the light source 403 that emits light not only from the side surface 434 b but also from the upper side 434 a can be accommodated in the accommodation hole 402 extending in the thickness direction of the light guide plate 401 without impairing the light emission efficiency.

  Further, according to the present embodiment, since heat generated by the light source 403 is dissipated in the aluminum frame 441 installed in parallel with the light guide plate 401, it is possible to obtain a good heat dissipation characteristic and to realize a reduction in thickness. . Further, since the white reflective sheet 454 is interposed between the aluminum frame 441 and the light guide plate 401, the light in the light guide plate 401 can be accurately reflected to the upper surface 411 side. Furthermore, since the upper surface 411 of the light guide plate 401 is covered with the white reflective sheet 455, uniform white light is emitted from the white reflective sheet 455 to the outside.

  Further, according to the present embodiment, the LED element 32 of the light source 403 is mounted by flip chip connection, and the light source 403 is not provided with a special optical system for radiation in the lateral direction. And the diameter of the accommodation hole 402 can be reduced. As a result, it is possible to mount the light source 403 with the optical axis in the thickness direction without increasing the thickness of the light guide plate 401. In addition, since the accommodation hole 402 of the light guide plate 401 does not have a special optical system and the hole perpendicular to the light guide plate 401 is merely formed, the accommodation hole 402 of the light source 403 and the light guide plate 401 is compared with the entire light guide plate 401. It can be inconspicuous. In addition, since it is not necessary to optically process the upper surface 434a and the side surface 434b of the light source 403, the light source 403 can be easily and easily manufactured. Furthermore, since the light source 403 is mounted with the optical axis in the thickness direction, it is possible to take a heat dissipation measure simply by mounting it on the aluminum frame 441 parallel to the light guide plate 401.

  In the second embodiment, although the white reflection sheet 455 is provided on the upper surface 411 of the light guide plate 401, it may be omitted as shown in FIG. 17, for example. For example, as shown in FIG. 17, the lower surface 412 side of the light guide plate 401 is fixed to the ceiling or the like, and for example, does not emit light at 45 ° or more, preferably 30 ° or more with respect to the optical axis of the light source 403. As long as the user or the like does not look up the light source 403 with high brightness and light, the light source 403 is not directly visible, and light is directly emitted from the housing hole 402 to the outside. On the other hand, by making the entire light guide plate 401 emit light, it is possible to obtain a lamp that does not cause glare. If the light distribution characteristic of the light source 403 is axisymmetric, the inner surface 421 of the receiving hole 402 is assumed to emit no light at 45 ° or more, preferably 30 ° or more with respect to the optical axis of the light source 403. The solid angle with respect to the central portion of the upper surface 434a of the light source 403 is 4.44 steradian, preferably 5.44 steradian.

  In the second embodiment, the horizontally long light sources 403 are arranged in a row in the horizontal direction. However, for example, as shown in FIG. 18, the light sources 403 are arranged in the vertical direction or arranged in a plurality of rows. Alternatively, the arrangement of the light sources is arbitrary. Also, the light source 403 and the light receiving plate 401 can be used as accents for relatively inconspicuous ones, and they look good by being arranged at a uniform interval, a regular patterning arrangement, or a random arrangement. Can also be improved.

  Here, in the light emitting device 500 of FIG. 18, the diffuser plate 556 is provided on the upper surface 411 of the light guide plate 401 instead of the white reflective sheet 455. As shown in FIG. 19, a diffusion accelerating portion 556 a that has been subjected to uneven processing is formed in a portion of the diffusion plate 556 that closes the accommodation hole 402. The diffusion promoting portion 556a can also be formed by applying a diffusion paint. According to the light emitting device 500, the light in the accommodation hole 402 can be diffused effectively, and the light emitted from the diffusion plate 556 to the outside can be made more uniform while improving the light extraction efficiency. .

  Moreover, in the said embodiment, although the light-emitting device using a LED element was demonstrated as a light-emitting element, a light-emitting element is not limited to a LED element, In addition, a concrete detailed structure etc. can be changed suitably. Of course.

DESCRIPTION OF SYMBOLS 1 Light guide plate 2 Accommodating hole 3 Light source 4 Mounting board 11 Upper surface 12 Lower surface 21 Inner surface 31 Solder 32 LED element 33 Element mounting substrate 34 Glass sealing part 34a Upper surface 34b Side surface 35 Glass before sealing 35a Concave part 36 Intermediate body 37 Resin sealing part 38 Inorganic paste 39 Wire 41 Substrate body 42 Insulating layer 43 Circuit pattern 44 White resist layer 51 Reflector plate 52 Reflector plate 53 Reflector plate 91 Lower mold 92 Upper mold 200 Light emitting device 206 Reflecting unit 300 Light emitting device 301 Light guide plate 311 Upper surface 312 Lower surface 400 Light emitting device 401 Light guide plate 402 Accommodating hole 403 Light source 411 Upper surface 412 Lower surface 421 Inner surface 431 Heat radiation pattern 433 Element mounting substrate 434 Glass sealing portion 434a Upper surface 434b Side surface 441 Aluminum frame 441a Flange portion 441b Flange portion 442 Mounted Substrate 454 white reflecting sheet 455 white reflecting sheet 500 emitting device 556 diffusion plate 556a diffusion enhancing portion

Claims (7)

A light source having an element mounting substrate, an LED element mounted on the element mounting substrate by flip chip connection, and a sealing portion for sealing the LED element on the element mounting substrate;
A light guide plate having an accommodation hole in which the light source is accommodated,
The accommodation hole extends from one surface of the light guide plate to the other surface side, and a range of light incident from the light source on the inner surface is parallel to the thickness direction of the light guide plate,
The light source is housed in the housing hole so that the element mounting substrate is on the other surface side of the light guide plate, and emits light to one surface side of the light guide plate of the housing hole and the inner surface side of the housing hole, And the optical axis is parallel to the thickness direction of the light guide plate,
The solid angle of the inner surface of the receiving hole with respect to the center portion of the upper surface of the light source is 4.44 steradian or more.   The light emitting device according to claim 1, wherein the accommodation hole is formed through the light guide plate.   The light-emitting device according to claim 2, further comprising a mounting substrate that is provided on one surface side of the light guide plate and on which the light source is mounted.   The light emitting device according to claim 3, wherein the sealing portion is heat-sealing glass.   The light-emitting device according to claim 4, wherein the light source has a rectangular parallelepiped shape.   The light emitting device according to claim 4 or 5, wherein a phosphor that converts a wavelength of light emitted from the LED element is dispersed in the sealing portion.   The light emitting device according to any one of claims 3 to 6, further comprising a reflecting plate that is provided on the other surface side of the light guide plate and closes the accommodation hole.

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