JP2008300570A - Light emitting device - Google Patents

Abstract

There is provided a light emitting device capable of suppressing a decrease in luminous efficiency of a phosphor due to a temperature rise of the phosphor and capable of increasing a light output.
An LED chip, a mounting substrate on which the LED chip is mounted, and a phosphor that emits light of a color different from the emission color of the LED chip when excited by light emitted from the LED chip. And a color conversion member 30 disposed between the mounting substrate 20 and the LED chip 10. The color conversion member 30 is a radiated light vector to the normal line U set at the intersection of the extended line of the radiated light vector r representing the direction and intensity of the radiated light from the LED chip 10 and the inner surface 31 of the color conversion member 30. the length of the orthogonal projection r _a of r is the shape of the inner surface 31 so as to be constant are set.
[Selection] Figure 1

Description

  The present invention relates to a light emitting device using an LED chip (light emitting diode chip).

  Conventionally, a GaN LED chip that emits blue light or ultraviolet light, and a phosphor or light absorption as a wavelength conversion material that emits light of an emission color different from that of the LED chip when excited by light emitted from the LED chip. Research and development of a light emitting device that emits light of a color different from the light emission color of an LED chip, including white, by combining with a body has been performed in various places (for example, Patent Document 1). Note that this type of light-emitting device has advantages such as small size, light weight, and power saving. For example, a light source that is an alternative to a small light bulb (incandescent light bulb, halogen light bulb, etc.) Light).

  In addition, when using a light emitting device capable of obtaining white light as a light source for illumination, etc., an LED unit in which a large number of light emitting devices are mounted side by side on a wiring board is configured to increase the amount of light as a whole LED unit. However, as the number of light-emitting devices increases, the cost including manufacturing costs increases, and there is a problem that the lens and the reflecting mirror are enlarged when the light from the light-emitting devices is desired to be spotted.

  Therefore, in the LED unit described above, while reducing the number of light emitting devices, the input power to the light emitting device is increased so as to obtain a desired light output so that the junction temperature of the LED chip does not exceed the maximum junction temperature. It is common.

  In Patent Document 1, as shown in FIG. 3, the LED chip 10 ′ is enclosed between the LED chip 10 ′, the mounting substrate 20 ′ on which the LED chip 10 ′ is mounted, and the mounting substrate 20 ′. There is described a light emitting device including a dome-shaped sealing member 40 ′ arranged in a shape and a color conversion layer 41 ′ made of a phosphor layer formed on the inner surface of the sealing member 40 ′.

Conventionally, as shown in FIG. 4, a color conversion layer 141 ′ composed of a light emitting diode 110 ′ and a phosphor layer containing a phosphor that is excited by light emitted from the light emitting diode 110 ′ to emit light is provided. A light-transmitting globe 140 ′ hermetically sealed on the surface, the light emitting diode 110 ′ is formed in a structure having a light distribution curve of uniform diffusion, and the globe 140 ′ is a light distribution curve of the light emitting diode 110 ′. A light bulb-shaped LED lamp formed in an outer shape substantially similar to the above has been proposed (Patent Document 2).
JP 2007-49019 A JP 2005-108700 A

  By the way, in the light emitting device having the configuration shown in FIG. 3, when the input power is increased, the radiant energy of blue light or ultraviolet light radiated from the LED chip 10 ′ increases, resulting in energy loss due to Stokes shift in the phosphor. The total amount of heat generated is increased, and the temperature of the color conversion layer 41 ′ increases.

  However, in the light emitting device having the configuration shown in FIG. 3, only the end of the color conversion layer 41 ′ formed on the inner surface of the dome-shaped sealing member 40 ′ is in contact with the mounting substrate 20 ′. The heat generated in the phosphor 41 'cannot be efficiently dissipated to the mounting substrate 20' by heat transfer, the phosphor temperature rises and the luminous efficiency of the phosphor decreases, and is output from the entire apparatus. There was a problem that the amount of light decreased. Here, the temperature rise of the color conversion layer 41 ′ is particularly likely to occur at a portion away from the mounting substrate 20 ′ and where the incident light intensity per unit area is high.

  Therefore, the technology for making the light distribution curve of the light emitting diode 110 ′ and the shape of the inner surface of the color conversion layer 141 ′ described in Patent Document 2 substantially similar to the light emitting device having the configuration shown in FIG. 3 is applied. However, when the light distribution of the light emitted from the LED chip 10 ′ is non-uniform, the portion of the inner surface of the color conversion layer 41 ′ having a high incident light intensity per unit area is the mounting substrate 20 ′. It will occur in the place away from.

  The present invention has been made in view of the above reasons, and an object of the present invention is to provide a light emitting device capable of suppressing a decrease in light emission efficiency of a phosphor due to a temperature rise of the phosphor and increasing a light output. It is in.

  The invention of claim 1 includes an LED chip, a mounting substrate on which the LED chip is mounted, and a phosphor that emits light of a color different from the emission color of the LED chip when excited by light emitted from the LED chip. And a color conversion member arranged to surround the LED chip between the mounting substrate and the color conversion member, and the color conversion member represents the direction and intensity of the emitted light from the LED chip. The shape of the inner surface is set so that the length of the orthogonal projection of the emitted light vector to the normal line established at the intersection of the extended line of the emitted light vector and the inner surface of the color conversion member is constant. Features.

  According to the present invention, the color conversion member is a radiated light vector to a normal line set at the intersection of an extended line of the radiated light vector representing the direction and intensity of the radiated light from the LED chip and the inner surface of the color conversion member. Since the shape of the inner surface is set so that the length of the orthogonal projection is constant, the incident light intensity per unit area of the inner surface of the color conversion member can be made substantially constant, and the temperature of the phosphor A decrease in the luminous efficiency of the phosphor due to the rise can be suppressed, and the light output can be increased.

  According to the first aspect of the invention, it is possible to suppress a decrease in the luminous efficiency of the phosphor due to the temperature rise of the phosphor, and to increase the light output.

(Embodiment 1)
As shown in FIG. 1, the light emitting device of the present embodiment includes an LED chip 10, a mounting substrate 20 on which the LED chip 10 is mounted, and a light emission color of the LED chip 10 when excited by light emitted from the LED chip 10. A color conversion member 30 comprising a dome-shaped translucent member containing a phosphor that emits light of a color different from that of the LED chip 10 and the mounting substrate 20, and a color conversion member 30 and a gel-like sealing portion (not shown) made of a sealing material (for example, silicone resin) that is filled in a space surrounded by the mounting substrate 20 and seals the LED chip 10 and the like. .

  The mounting substrate 20 is formed by using an insulating substrate 21 made of a rectangular plate-shaped ceramic substrate (for example, a ceramic substrate having electrical insulation and high thermal conductivity such as an alumina substrate or an aluminum nitride substrate). The two wiring patterns 22 and 22 that are electrically connected to the respective electrodes of the LED chip 10 are formed. Here, each wiring pattern 22, 22 is formed across one surface (upper surface in FIG. 1), side surface, and the other surface (lower surface in FIG. 1), and each wiring pattern 22, 22. Of these, portions formed across the side surface and the other surface constitute the external connection electrodes 22b and 22b. Each of the wiring patterns 22 and 22 includes a Cu film and an Au film on the Cu film. The insulating substrate 21 is not limited to a ceramic substrate, and an epoxy resin substrate, a hollow substrate, or the like may be used.

  Further, in the light emitting device of this embodiment, a rectangular heat radiating conductor portion 26 for radiating heat generated in the LED chip 10 is formed in the central portion of the other surface of the insulating substrate 21 in the mounting substrate 20. Therefore, when mounting on a wiring board (not shown), the heat dissipating conductor part 26 is fixed to the conductor pattern of the wiring board through a joint portion made of solder and thermally coupled to the wiring board, whereby the LED chip 10 Temperature rise can be suppressed. The heat radiating conductor 26 is formed of the same material as the wiring patterns 22 and 22. Further, the heat dissipating conductor portion 26 is set to have a larger planar size than the LED chip 10.

  On the other hand, the LED chip 10 is a GaN-based blue LED chip that emits light in a blue wavelength range, and a light-emitting portion made of a GaN-based compound semiconductor material on one surface side of a base substrate made of a sapphire substrate that is a crystal growth substrate. Each electrode is electrically connected to the wiring patterns 22 and 22 of the mounting substrate 20 via bumps 16 and 16 made of a metal material (Au in this embodiment).

  The color converting member 30 is excited by absorbing blue light emitted from the LED chip 10 in a translucent material such as silicone resin, and emits yellow light having a lower energy than blue light. It is comprised by the translucent member containing a body. Therefore, in the light emitting device of the present embodiment, the blue light emitted from the LED chip 10 and the yellow light emitted from the yellow phosphor are emitted through the outer surface (light emitting surface) 32 of the color conversion member 30. White light can be obtained. The translucent material used as the material of the color conversion member 30 is not limited to the silicone resin, and for example, an epoxy resin, glass, or the like may be employed. Further, the phosphor contained in the translucent material used as the material of the color conversion member 30 is not limited to the yellow phosphor, and a plurality of types of phosphors may be used for the purpose of improving color adjustment and color rendering. White light with high color rendering properties can be obtained by using a red phosphor and a green phosphor. Here, when a plurality of types of phosphors are used, the phosphor is not necessarily a combination of phosphors having different emission colors, and for example, a plurality of types of phosphors having an emission color of yellow and different emission spectra may be combined.

  The color conversion member 30 described above is bonded to the mounting substrate 20 using an adhesive (for example, a silicone resin, an epoxy resin, or the like) over the entire periphery of the opening.

  In the light emitting device of the present embodiment, a high output type GaN-based blue LED chip with a chip size of 1 mm □ is used as the LED chip 10, so that the junction temperature of the LED chip 10 does not exceed the maximum junction temperature and The input power to the LED chip 10 is set to about 1 to 3 W, for example, so as to obtain a desired light output.

  By the way, the color conversion member 30 has a top portion 30a formed in a hollow conical shape, a peripheral portion 30b formed in a spherical band shape, and a lower end portion of the top portion 30a and an upper end portion of the peripheral portion 30b are smoothly continuous. ing. In this embodiment, the thickness of the color conversion member 30 is constant at 0.5 mm, the inner diameter of the peripheral portion 30b of the color conversion member 30 is 4 mm, and the outer diameter is 5 mm. However, these numerical values are examples. There is no particular limitation.

Here, the color conversion member 30 and the LED chip 10 are arranged so that their optical axes coincide with each other, and the color conversion member 30 is a radiated light vector r representing the direction and intensity of the radiated light from the LED chip 10. is set the shape of the inner surface 31 so that the length of the orthogonal projection r _a of the extension line and the emitted light vector r in the normal U stood at the intersection of the inner surface 31 of the color conversion member 30 is constant ing. The emitted light vector r represents the light intensity in each direction of the LED chip 10 as a light source by the direction and length of an arrow, and the envelope surface at the tip of the arrow is a light distribution solid (light distribution pattern) D. Represents.

Or more light-emitting device of the present embodiment described, the orthogonal projection r _a of the radiation vector r in the normal U stood at the intersection of the inner surface 31 of the extension line and the color conversion member 30 of the above-mentioned emitted light vector r Since the shape of the inner surface 31 of the color conversion member 30 is set so that the length is constant, the incident light intensity per unit area of the inner surface 31 of the color conversion member 30 can be made substantially constant, A decrease in the luminous efficiency of the phosphor due to the temperature rise of the phosphor can be suppressed, and an increase in light output can be achieved.

  Further, in the light emitting device of this embodiment, when the entire inner surface 31 of the color conversion member 30 is formed in a shape that forms a part of one spherical surface (in short, the color conversion member 30 is a hollow hemisphere). The surface area of the color conversion member 30 can be increased, and the heat generated by the phosphor in the color conversion member 30 is efficiently transferred from the outer surface 32 side of the color conversion member 30 to the atmosphere. The heat can be dissipated well, and a decrease in light emission efficiency, a color shift, and a decrease in reliability due to a temperature rise of the phosphor can be suppressed.

  Moreover, in the light emitting device of this embodiment, since the ceramic substrate having high thermal conductivity is used as the insulating substrate 21 in the mounting substrate 20 as described above, the heat generated in the LED chip 10 can be efficiently dissipated. it can.

  In the present embodiment, the space surrounded by the mounting substrate 20 and the color conversion member 30 is enriched by the sealing portion that seals the LED chip 10. However, the space is filled with an air atmosphere, an inert gas atmosphere, A vacuum atmosphere may be used.

(Embodiment 2)
The basic configuration of the light emitting device of the present embodiment shown in FIG. 2 is substantially the same as that of the first embodiment, the shape of the light distribution solid (light distribution pattern) D of the LED chip 10 is different, and the shape of the color conversion member 30 is different. To do. In addition, the same code | symbol is attached | subjected to the component similar to Embodiment 1, and description is abbreviate | omitted.

  In the LED chip 10 according to the present embodiment, the shape of the light distribution solid D is as shown in FIG. 2, and the light intensity is maximum in the direction where the emission angle is about 45 degrees. On the other hand, in the color conversion member 30, as in the first embodiment, the intersection of the extended line of the emitted light vector representing the direction and intensity of the emitted light from the LED chip 10 and the inner surface 31 of the color conversion member 30. The shape of the inner surface 31 is set so that the length of the orthogonal projection of the radiated light vector to the normal line standing at a constant angle is set, and the opening area gradually increases as the peripheral portion 30b approaches the top portion 30a. It is formed in a cylindrical shape, and the top portion 30a is formed in a gently curved shape so as to protrude toward the LED chip 10 side.

  Thus, in the light emitting device of this embodiment, as in the light emitting device of Embodiment 1, the incident light intensity per unit area of the inner surface 31 of the color conversion member 30 can be made substantially constant, and the temperature of the phosphor A decrease in the luminous efficiency of the phosphor due to the rise can be suppressed, and the light output can be increased.

  By the way, in each above-mentioned embodiment, although the blue LED chip whose luminescent color is blue is employ | adopted as LED chip 10, the luminescent color of LED chip 10 is not restricted to blue, For example, ultraviolet light may be sufficient. Moreover, in each embodiment, although the sapphire substrate is employ | adopted as a base substrate in LED chip 10, a base substrate is not restricted to a sapphire substrate, A SiC substrate etc. may be sufficient. Further, the base substrate is not limited to the crystal growth substrate, and may be a Si substrate or the like bonded to the light emitting portion after crystal growth (in this case, the crystal growth substrate is removed). In each embodiment, the LED chip 10 is flip-mounted on the mounting substrate 20, but a mounting structure using a bonding wire may be adopted.

1 is a schematic cross-sectional view of a light emitting device according to Embodiment 1. FIG. 6 is a schematic cross-sectional view of a light emitting device according to Embodiment 2. FIG. It is a schematic sectional drawing of the light-emitting device which shows a prior art example. It is a schematic sectional drawing of the light-emitting device which shows another prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 LED chip 20 Mounting board 30 Color conversion member 30a Top part 30b Peripheral part 31 Inner surface 32 Outer surface D Light distribution solid r Radiation vector r _a Orthographic U Normal

Claims (1)

  A dome-like light-transmitting material including an LED chip, a mounting substrate on which the LED chip is mounted, and a phosphor that emits light of a color different from the emission color of the LED chip when excited by light emitted from the LED chip And a color conversion member disposed between the mounting substrate and the LED chip so as to surround the LED chip, and the color conversion member includes an extension line of a radiated light vector representing the direction and intensity of the radiated light from the LED chip; A light-emitting device, wherein the shape of the inner surface is set so that the length of the orthogonal projection of the emitted light vector to the normal line set at the intersection with the inner surface of the color conversion member is constant.

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