(12) United States Patent
`Nii et al.
`
`(10) Patent No.:
`(45) Date of Patent:
`
`US 7,815,343 B2
`Oct. 19, 2010
`
`USOO7815343B2
`
`(54) LIGHT EMITTING DEVICE
`(75) Inventors: Ikuya Nii, Anan (JP); Hiroaki Ukawa,
`Tokushima (JP); Nobuhide Kasae,
`Tokushima (JP); Toshimasa Takao,
`Tokushima (JP)
`Assignee: Nichia Corporation, Anan-shi (JP)
`
`(73)
`(*)
`
`(21)
`(22)
`(65)
`
`Notice:
`
`Subject to any disclaimer, the term of this
`patent is extended or adjusted under 35
`U.S.C. 154(b) by 497 days.
`Appl. No.: 11/882,603
`Filed:
`Aug. 2, 2007
`
`Prior Publication Data
`US 2008/OO37252A1
`Feb. 14, 2008
`
`Foreign Application Priority Data
`(30)
`Aug. 4, 2006
`(JP)
`........................... P2006-213929
`
`(51)
`
`(52)
`
`(58)
`
`(56)
`
`Int. C.
`(2006.01)
`F2IV3/00
`U.S. Cl. ............................ 362/311.03; 362/249.02;
`362/255; 362/256; 362/267; 362/3.11.02;
`362/3.11.04; 257/98: 257/99; 257/100
`Field of Classification Search ................. 362/267,
`362/311.02, 231, 249.02, 255, 256, 293,
`362/3.11.03, 311.04; 313/502; 427/64; 257/98,
`257/99, 100
`See application file for complete search history.
`References Cited
`
`U.S. PATENT DOCUMENTS
`
`6,610,563 Bl
`
`8/2003 Waitl et al. .................. 438,166
`
`7,554,129 B2 * 6/2009 Roth et al. .................. 257/100
`7,592,639 B2* 9/2009 Maeda et al. ...
`... 257/98
`2004/005.1111 A1
`3f2004 Ota et al. ...................... 257/98
`
`2005/0173713 A1* 8, 2005 Lin et al. ...................... 257/81
`2005/0280354 A1* 12/2005 Liu ............................ 313/5O2
`2006/0022215 A1
`2/2006 Arndt et al.
`2006/0022580 A1
`2/2006 Jermann et al. ............. 313/5O1
`2006/025571.6 A1* 11/2006 Tsutsumi et al. ......
`... 313,502
`2007/00 19416 A1
`1/2007 Han et al. ................... 362,307
`
`FOREIGN PATENT DOCUMENTS
`
`T 2006
`
`JP
`2006-516816. A
`* cited by examiner
`Primary Examiner Sandra L. O'Shea
`Assistant Examiner Mary Zettl
`(74) Attorney, Agent, or Firm—Birch, Stewart, Kolasch &
`Birch, LLP
`
`(57)
`
`ABSTRACT
`
`The present invention provides a light emitting device which
`has high reliability and long service life by Suppressing the
`sealing resin from peeling off the inner edge of the opening of
`the recess of the housing.
`The light emitting device of the present invention comprises
`a light emitting element having a pair of electrodes, a housing
`having a recess for accommodating the light emitting ele
`ment, a first lead electrode and a second lead electrode which
`are exposed on the bottom of the recess, electrically conduc
`tive members for electrically connecting the pair of electrodes
`of the light emitting element to the first lead electrode and to
`the second lead electrode respectively, a transparent sealing
`material which fills in the recess and granular additives con
`tained in the sealing material, wherein the inner wall Surface
`of the recess has a light blocking section that blocks light
`emitted by the light emitting device toward the inner edge of
`the opening of the recess, the quantity of the granular addi
`tives contained in the sealing material is controlled to such a
`level that enhances scattering of light in a first region located
`below the light blocking section and to such a level that
`
`e 11gnt block1ng Secuon.
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`19 Claims, 14 Drawing Sheets
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`Nichia Exhibit 1010
`Page 1
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`

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`U.S. Patent
`
`Oct. 19, 2010
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`Sheet 1 of 14
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`US 7,815,343 B2
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`Fig. 1A
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`Nichia Exhibit 1010
`Page 2
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`

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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 2 of 14
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`US 7,815,343 B2
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`
`
`Fig. 1C
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`Page 3
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`

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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 3 of 14
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`US 7,815,343 B2
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`Fig. 2A
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`Nichia Exhibit 1010
`Page 4
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`

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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 4 of 14
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`US 7,815,343 B2
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`Fig. 3A
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`Nichia Exhibit 1010
`Page 5
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`Fig. 3B
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`Nichia Exhibit 1010
`Page 6
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet6 of 14
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`US 7,815,343 B2
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`Fig. 4
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`Nichia Exhibit 1010
`Page 7
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`Nichia Exhibit 1010
`Page 7
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 7 of 14
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`US 7,815,343 B2
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`Fig. 5
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`Nichia Exhibit 1010
`Page 8
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`Nichia Exhibit 1010
`Page 8
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`Nichia Exhibit 1010
`Page 9
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`Nichia Exhibit 1010
`Page 9
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 9 of 14
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`US 7,815,343 B2
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`Fig. 7A
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`Nichia Exhibit 1010
`Page 10
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 10 of 14
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`US 7,815,343 B2
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`Nichia Exhibit 1010
`Page 11
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`Nichia Exhibit 1010
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`US 7,815,343 B2
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`Nichia Exhibit 1010
`Page 12
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`U.S. Patent
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`Oct. 19, 2010
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`Fig. 9A
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`Sheet 12 of 14
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`US 7,815,343 B2
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`Nichia Exhibit 1010
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`Nichia Exhibit 1010
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 13 of 14
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`US 7,815,343 B2
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`Fig. 9C
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`Nichia Exhibit 1010
`Page 14
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`U.S. Patent
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`Oct. 19, 2010
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`Sheet 14 of 14
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`US 7,815,343 B2
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`Nichia Exhibit 1010
`Page 15
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`

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`US 7,815,343 B2
`
`1.
`LIGHT EMITTING DEVICE
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`The present invention relates to a light emitting device, and
`particularly to a light emitting device having high heat resis
`tance and high durability.
`2. Description of the Related Art
`Among light emitting devices that employ light emitting
`elements such as light emitting diode, a light emitting device
`having a housing which protects the to the light emitting
`element is known. The housing has a recess formed on the
`light emitting side thereof so that, after the light emitting
`element is mounted in the recess, the recess is filled with a
`transparent sealing material for the protection of the light
`emitting element from the environment.
`The housing is formed from an electrically insulating resin
`which is appropriate for electrically and mechanically pro
`tecting the light emitting element. For example, a nylon
`based resin Such as polyphthalamide or polyamide, a liquid
`crystal polymer, or an epoxy-based resin is preferably used.
`For the sealing material. Such a material is used that has
`translucency and good bonding with the housing, and an
`epoxy resin is commonly used. While the epoxy resin is
`known to undergo deterioration and discoloration to become
`yellowish when exposed to light and/or heat over an extended
`period of time, this problem may be negligible if used in a
`light emitting device of which intensity of light emission is
`not high and heat generation is low.
`However, as light emitting devices are manufactured with
`increasingly higher output power, the epoxy resin used as the
`sealing material undergoes more significant yellowing, which
`results in a decrease in the light transmittance of the epoxy
`resin. As a result, efficiency of extracting light from the light
`emitting device decreases. In the case of a light emitting
`device which emits light of shorter wavelength, in particular,
`yellowing due to the deterioration and decrease in the light
`transmittance become substantial. While service life of the
`light emitting device has been increasing, there has been Such
`a problem that the epoxy resin has lower durability than the
`other components of the light emitting device.
`Accordingly, it has been proposed to use a silicone resin,
`which is transparent and is less vulnerable to deterioration
`due to light and heat, instead of the epoxy resin as the sealing
`material (for example, refer to Kohyo (National Publication
`of Translated Version) No. 2006-516816). The silicone resin
`has siloxane bond of high bonding energy in the backbone of
`base polymer, and is one of resins which have high heat
`resistance and high weatherability. The silicone resin also has
`highlight transmittance, and is regarded as a promising seal
`ing material to be used in light emitting devices of high output
`power.
`However, the silicone resin which has high translucency
`and high durability also as a drawback of low bonding with
`the housing. That is, when the silicone resin is used as the
`sealing material, it may peel off first in the inner edge of
`opening of the recess and then in the inner portion of the
`recess, due to the mechanical and thermal stresses caused
`between the housing and the sealing material. In the worst
`case, the sealing resin may completely fall off the housing.
`As a technique to solve this problem, it is known to provide
`a wall around the recess of the housing and a ring-shaped
`trench between the wall and the inner edge of the opening (for
`example, refer to Kohyo (National Publication of Translated
`Version) No. 2006-516816). The sealing material is provided
`to fill not only the recess of the housing but also the trench, so
`
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`as to serve as an anchor ring. In this housing, the wall is
`formed so that the top of the wall is lower than the light
`emitting surface of the housing when viewed from the bottom
`of the recess.
`Peel-offbetween the inneredge of the opening of the recess
`of the housing and the sealing material may lead to the infil
`tration of moisture and impurities into the light emitting
`device, as well as to causing the separation of the sealing
`material to start. When moisture or other impurity which has
`infiltrated through a peeling gap deposits on the inner Surface
`of the recess, reflectivity of the housing decreases which
`results in decreasing efficiency of extracting light from the
`light emitting device. When the impurity reaches the light
`emitting element, the light emitting device may fail to func
`tion. The technology disclosed in Kohyo (National Publica
`tion of Translated Version) No. 2006-516816 may suppress
`the sealing member from peeling off in the interface with the
`housing and falling off, although it is unable to prevent peel
`off on the inner edge of the opening of the recess of the
`housing.
`In case the silicone resin is used for the sealing resin, in
`particular, the problem of moisture or other impurity infiltrat
`ing through a peeling gap becomes serious, since the silicone
`resin has higher expansion coefficient than the housing. As
`the temperature of the light emitting device rises during
`operation, the silicone resin expands more than the housing
`and Swells outwardly from the inner edge of the opening of
`the recess of the housing. In case there is a gap between the
`sealing resin and the inner edge of the opening of the recess of
`the housing due to peeling, the sealing resin bulges out of the
`housing as the temperature of the light emitting device rises.
`Then, the sealing resin returns within the housing as the
`temperature decreases. As this thermal cycle is repeated,
`bonding between the sealing resin and the inner edge of the
`opening of the recess of the housing is lost, thus allowing
`impurities to enter through the gap.
`
`SUMMARY OF THE INVENTION
`
`An object of the present invention is to provide a light
`emitting device which has high reliability and long service
`life, and is capable of Suppressing impurities from entering
`the light emitting device by Suppressing the sealing resin from
`peeling off the inner edge of the opening of the recess of the
`housing.
`The present invention is based on a finding that exfoliation
`of the sealing resin from the inner edge of the opening of the
`recess of the housing is accelerated significantly by the dete
`rioration of the material forming the inner edge of the open
`ing, and the deterioration is caused to proceed by the light
`emission from the light emitting device. Accordingly, the
`present invention is intended to Suppress the deterioration of
`the material forming the inner edge of the opening by reduc
`ing light emission which illuminates the inner edge of the
`opening of the recess of the housing, thereby to Suppress the
`sealing resin from peeling off the inner edge of the opening.
`In the conventional light emitting device, too, it has been
`attempted to reduce direct illumination of the inner wall sur
`face of the recess of the housing by the light emitted by the
`light emitting device, by scattering the light directly coming
`from the light emitting element by means of fluorescent mate
`rial particles added in the sealing resin or a filler contained in
`the resin for the adjustment of viscosity. The fluorescent
`material particles absorb light emitted by the light emitting
`device and emit light in the radiating direction, and therefore
`have significant effect of reducing the intensity of light
`directly incident on the inner wall surface. However, scatter
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`Nichia Exhibit 1010
`Page 16
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`US 7,815,343 B2
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`15
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`3
`by the granular particles added in the resin is not enough to
`Suppress the sealing resin from peeling off the inner edge of
`the opening of the recess.
`The present invention provides a light emitting device
`which enhances the blocking of light directly directed toward
`the inner edge of the opening in the inner wall Surface of the
`recess, while exhibiting ordinary light diminishing effect as
`in the prior art for light directly incident on the other portion
`of the inner wall.
`First, light emitting device of the present invention com
`10
`prises a light emitting element having a pair of electrodes, a
`housing having a recess for accommodating the light emitting
`element, a first lead electrode and a second lead electrode
`which are exposed on the bottom of the recess, electrically
`conductive members for electrically connecting the pair of
`electrodes of the light emitting element to the first lead elec
`trode and to the second lead electrode respectively, a trans
`parent sealing material which fills in the recess and granular
`additives contained in the sealing material, wherein the inner
`wall Surface of the recess has a light blocking section that
`blockslight emitted by the light emitting device from directly
`illuminating the inner edge of the opening of the recess,
`quantity of the granular additives contained in the sealing
`material is controlled to Such a level that enhances scattering
`of light in a first region located below the light blocking
`section and to Such a level that Suppresses scattering of light
`in a second region located above the light blocking section.
`In the first light emitting device of the present invention, the
`light blocking section is disposed so as to prevent the inner
`edge of the opening from being directly illuminated by the
`light emitted by the light emitting device. As a result, the light
`emitted by the light emitting device is prevented by the light
`blocking section from directly reaching the inner edge of the
`opening, so that deterioration of the material in the inner edge
`of the opening is Suppressed very effectively.
`As the quantity of the granular additives contained in the
`sealing material that fills the first region located below the
`light blocking section is controlled to Such a level that is
`enough to scatter light, and therefore it is made possible to
`scatter the light directly coming from the light emitting
`device, and reduce direct illumination of the inner wall Sur
`face of the recess of the housing by light from the light
`emitting device. Also, as the quantity of the granular additives
`contained in the sealing material that fills the second region
`located above the light blocking section is controlled to such
`a level that has no significant effect on the scattering of light,
`it is made possible to Suppress light which has been scattered
`by the granular additives contained in the sealing material that
`fills the second region from reaching the inner edge of the
`opening and thereby Suppressing the material forming the
`inner edge of the opening from degrading.
`As used herein, the phrase “to block light' means, in addi
`tion to complete blocking of light from the light emitting
`element directed toward the inner edge of the opening, partial
`blocking of light as well.
`55
`Second, light emitting device of the present invention com
`prises a light emitting element having a pair of electrodes, a
`housing having a recess for accommodating the light emitting
`element, a first lead electrode and a second lead electrode
`which are exposed on the bottom of the recess, electrically
`conductive members for electrically connecting the pair of
`electrodes of the light emitting element to the first lead elec
`trode and to the second lead electrode respectively, a trans
`parent sealing material which fills in the recess and a granular
`additives contained in the sealing material, wherein the inner
`wall Surface of the recess has a light blocking section that
`blocks light emitted by the light emitting device from illumi
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`nating the inner edge of the opening of the recess, the portion
`of the sealing material on the side of the bottom of the recess
`is formed as a first sealing layer that contains the granular
`additives, while thickness of the first sealing layeris in a range
`from 10% to 80% of the sealing material and the top surface
`of the first sealing layer is lower than the top end of the light
`blocking section.
`In the second light emitting device of the present invention,
`the light blocking section prevents the light emitted by the
`light emitting device from reaching the inner edge of the
`opening, so that deterioration of the material in the inner edge
`of the opening is Suppressed very effectively, similarly to the
`first light emitting device.
`In addition, disposing the first sealing layer containing the
`granular additives on the bottom of the recess of the sealing
`material makes it possible to scatter the light emitted by the
`light emitting device so as to reduce direct illumination of
`inner wall surface of the recess of the housing by light from
`the light emitting device. Also, since the thickness of the first
`sealing layer is set in a range from 10% to 80% of the sealing
`material, the first sealing layer that contains the granular
`additives completely covers the light emitting element while
`being concentrated in the vicinity of the light emitting ele
`ment, and therefore the effect of scattering the light emitted
`by the light emitting device is improved. Also, because the top
`surface of the first sealing layer is located lower than the top
`end of the light blocking section, the light emitted by the light
`emitting device, even when it is scattered by the granular
`additives, does not reach the inner edge of the opening and
`therefore the material forming the inner edge of the opening
`can be Suppressed from degrading.
`The phrase “thickness of the first sealing layer” is defined
`by assuming that the first sealing layer has a border at a
`position where concentration of the granular additives under
`goes abrupt change in macroscopic observation of a central
`portion of the recess filled with the sealing material. Macro
`scopic observation may be conducted by observing dark field
`image under a metallurgical microscope.
`Third, light emitting device of the present invention com
`prises a light emitting element having a pair of electrodes, a
`housing having a recess for accommodating the light emitting
`element, a first lead electrode and a second lead electrode
`which are exposed on the bottom of the recess, electrically
`conductive members for electrically connecting the pair of
`electrodes of the light emitting element to the first lead elec
`trode and to the second lead electrode respectively, a trans
`parent sealing material which fills in the recess and granular
`additives contained in the sealing material, wherein the inner
`wall Surface of the recess has a light blocking section that
`blocks light emitted by the light emitting device from illumi
`nating the inner edge of opening of the recess, maximum
`density of the granular additives having particle size of 2.0 um
`or larger contained in the sealing material is set lower in the
`second region located above the light blocking section than in
`the first region located below the light blocking section, and
`the maximum density of the granular additives contained in
`the second region is not higher than 80% of the maximum
`density of the granular additives in the first region.
`In the third light emitting device of the present invention,
`the light blocking section prevents the light emitted by the
`light emitting device from directly reaching the inner edge of
`the opening, so that deterioration of the material in the inner
`edge of the opening is Suppressed very effectively, similarly
`to the first to the second light emitting device.
`In the third light emitting device, maximum density of the
`granular additives having particle size of 2.0 um or larger
`contained in the sealing material is set lower in the second
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`Nichia Exhibit 1010
`Page 17
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`US 7,815,343 B2
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`6
`FIG. 8 is a top view schematically showing the light emit
`ting device according to the second variation of the second
`embodiment.
`FIG. 9A is a top view schematically showing the light
`emitting device according to the third embodiment.
`FIG.9B is a schematic sectional view taken along lines
`B-B in FIG.9A of the light emitting device according to the
`third embodiment.
`FIG. 9C is a schematic sectional view taken along lines
`C-C in FIG.9A of the light emitting device according to the
`third embodiment.
`FIG. 9D is a schematic sectional view taken along lines
`D-D in FIG.9A of the light emitting device according to the
`third embodiment.
`FIG. 10 is a photograph of a section of specimen according
`to Example 1.
`FIG. 11 is a photograph of a section of specimen according
`to Example 2.
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`5
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`region than in the first region, and the maximum density of the
`granular additives in the second region is set to 80% of the
`maximum density of the granular additives in the first region
`or less. This constitution makes it possible to enhance the
`scattering of light by the granular additives in the first region
`so as to reduce direct illumination of the inner wall surface of
`the recess of the housing by light from the light emitting
`device, and Suppress scattering in the second region so as to
`Suppress the illumination of the inner edge of the opening by
`the scattered light thereby suppressing the deterioration of the
`material of the inner edge of the opening.
`The term density refers to the number of particles,
`observed within a predetermined area (e.g. a square of 30 um)
`of a surface of the sealing resin revealed by cutting the light
`emitting device, divided by the area of the surface, given with
`a unit of number of particles perum.
`The maximum density is the highest value of density
`within the region under consideration. The granular particles
`may sediment toward the bottom before the sealing material
`hardens, depending on the particle size distribution and den
`sity of the granular particles and Viscosity of the sealing
`member. Sucha sedimentation results in Sucha distribution of
`the density of the granular additives and the density has the
`highest value in a portion where the granular particles have
`settled.
`The constitution of the present invention described above
`makes it possible to provide the light emitting device which
`has high reliability and long service life, since the sealing
`resin can be suppressed from peeling off the inner edge of the
`opening and impurities can be fended off from entering the
`light emitting device.
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`BRIEF DESCRIPTION OF THE DRAWINGS
`
`FIG. 1A is a perspective view schematically showing the
`light emitting device according to the first embodiment.
`FIG. 1B is a top view schematically showing the light
`emitting device according to the first embodiment.
`FIG. 1C is a schematic sectional view taken along lines
`X-X in FIG. 1B of the light emitting device according to the
`first embodiment.
`FIG. 2A is a top view schematically showing the light
`emitting device according to the first variation of the first
`embodiment.
`FIG.2B is a schematic sectional view taken along lines Y-Y
`in FIG. 2A of the light emitting device according to the first
`variation of the first embodiment.
`FIG. 3A is a perspective view schematically showing the
`light emitting device according to the second variation of the
`first embodiment.
`FIG. 3B is a top view schematically sowing the light emit
`ting device according to the second variation of the first
`embodiment.
`FIG. 4 is a top view schematically showing the light emit
`ting device according to the second embodiment.
`FIG. 5 is a top view schematically showing the light emit
`ting device according to the second embodiment.
`FIG. 6 is a top view schematically showing the light emit
`ting device according to the first variation of the second
`embodiment.
`FIG. 7A is a perspective view schematically showing the
`light emitting device according to the first variation of the
`second embodiment.
`FIG. 7B is a top view schematically showing the light
`emitting device according to the first variation of the second
`embodiment.
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`DESCRIPTION OF REFERENCE NUMERALS
`
`10: Light emitting device
`12: Housing
`12a: Light emitting Surface
`14: Recess
`16: Inner wall surface of the recess
`18: Bottom of the recess
`20: Inner edge of the opening
`22: Light blocking section
`24: Trench
`26: Transparent sealing material
`261: First sealing layer
`262: Second sealing layer
`28: Light emitting element
`30: Protective element
`32: Lead electrode
`320: External electrode
`34: Electrically conductive wires
`36: Protrusion
`38: Opening
`40: Edge of opening
`42: Notch
`R: First region
`R. Second region
`T: Thickness of first sealing layer
`T: Thickness of second sealing layer
`
`DESCRIPTION OF THE PREFERRED
`EMBODIMENTS
`
`First Embodiment
`
`A light emitting device 10 of this embodiment shown in
`FIG. 1A through 1C comprises a housing 12 having a recess
`14 with circular opening 38 and cross section of inverted
`trapezoid shape, and a plurality of lead electrodes 32 which
`are exposed on the bottom 18 of the recess 14. Disposed over
`the lead electrodes 32 are light emitting element 28 and a
`protective element 30 die-bonded thereon for electrically pro
`tecting the light emitting element 28, and are electrically
`connected with the lead electrodes 32 by means of electrically
`conductive wires 34. The light emitting element 28 is wire
`bonded by means of the electrically conductive wires 34 so as
`to be electrically connected to the lead electrodes 32 which
`are exposed on the bottom 18 of the recess 14. Since the lead
`electrodes 32 penetrate through the housing 12 and are con
`nected to external electrodes 320, electrical power can be
`
`Nichia Exhibit 1010
`Page 18
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`Supplied to the light emitting element 28 by applying a Volt
`age to the external electrodes 320.
`Formed between the inner wall surface 16 of the recess 14
`and the inner edge 20 of the opening is a continuous step
`having a ring shape when viewed from the front of the open
`ing of the recess, the step being used as the light blocking
`section 22. As used herein, the term “inner edge 20 of the
`opening” means an inner wall Surface 16 of the recess 14 in
`the vicinity of the opening 38, more specifically refers to the
`inner wall surface 16 in a range of up to 30% in depth of the
`recess 14 from the edge 40 of the opening 38 toward the
`bottom 18 of the recess 14. Depth of the recess 14 is the
`distance from the light emitting surface 12a to the bottom 18
`of the recess 14, and is represented in FIG. 1C by the sum of
`thickness of the first region R and thickness of the second
`region R.
`The light blocking section 22 is formed so that the top
`thereof is lower than the light emitting surface 12a of the
`housing 12. The light blocking section 22 is disposed so that
`the inner edge of the opening located right below the edge 40
`of the opening 38 would not be directly illuminated by the
`light from the light emitting element 28. Specifically, the light
`blocking section 22 is formed so as to surely block the light
`which would otherwise pass the line L-L connecting both
`ends of the light emitting Surface of the light emitting element
`28 and the edge 40 of the opening 38. Such blocking of light
`will be called total blocking of light in this specification. With
`this constitution, the light from the light emitting device 28 is
`blocked by the light blocking section 22, and does not reach
`the inner edge 20 of the opening. Thus the problem of the light
`from the light emitting device 28 directly illuminating the
`inner edge 20 of the opening thereby to degrade the bond
`between the inner edge 20 of the opening and the sealing
`material 26 is solved by the light blocking section 22.
`The light blocking section 22 shown in the drawing is
`formed with a height appropriate for total block of light
`incident on the inner edge 20 of the opening. Height of the
`light blocking section 22 is the distance between the bottom
`18 of the recess 14 and the top of the light blocking section 22,
`and is the same as the thickness of the first region R.
`The effect of Suppressing the sealing resin 26 from peeling
`off the inner edge 20 of the opening can be achieved suffi
`ciently also by partial blocking of light, instead of total block
`ing. With the constitution of the present invention, the light
`blocking section 22 having a height at least 80% of the height
`of the light blocking section 22 (which corresponds to thick
`ness of the first region R) required for total blocking of light
`can achieve Sufficient effect of Suppressing the peeling. This
`is because impurities can be prevented from entering the light
`emitting device 28 even when there is a slight peeling gap
`between the edge 40 of the opening 38 and the sealing resin 26
`as long as other portion in the region of the inner edge of the
`opening is prevented from peeling off, and therefore the
`object of the present invention to provide a light emitting
`device which has high reliability and long service life can be
`achieved. When height of the light blocking section 22 is less
`than 80% of the thickness of first region R, larger portion of
`the inner edge 20 of the opening is exposed to the direct light
`and may undergo peeling of the sealing resin 26 from the
`inner edge of the opening, thus increasing the possibility of
`infiltration by impurities.
`The recess 14 is filled with the transparent sealing material
`to a height higher than the light blocking section 22. That is,
`the transparent sealing material 26 filling the recess has a
`height Substantially equal to the light emitting Surface 12a of
`the housing 12 which is located higher than the top of the light
`blocking section 22. The sealing resin 26 has the function of
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`US 7,815,343 B2
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`protecting the light emitting device 28 from the environment.
`The recess 14 of the housing 12 is divided into the first region
`R located at a position lower than the top of the light blocking
`section 22 and the second region R, located at a position
`higher than the top of the light blocking section 22.
`The sealing material 26 contains various granular additives
`mixed therein for the purpose of controlling the properties of
`the sealing material. The granular additives used in the
`present invention include fluorescent material particles which
`absorb the light emitted by the light emitting device 28 and
`emit light of a different wavelength, a powdery dispersant
`which diffuses the light from the light emitting device 28 and
`granular oxide for controlling the physical properties such as
`Viscosity and thermal expansion coefficient. These materials
`may be used either individually or collectively.
`The materials used as the granular additives have a prop
`erty of Scattering light. As a result, the granular additives
`contained in the first region R in a large quantity would
`scatter the light directly incident from the light emitting
`device 28, so that the intensity of light that illuminates the
`inner wall surface 16 of the recess 14 is reduced. Thus, the
`effect of Suppressing the degradation of the material due to
`absorption of light by the inner wall surface 16 can be
`achieved. In the meantime, when the granular additives are
`contained in the