Source: http://www.google.com/patents/US7859185?dq=5,579,517
Timestamp: 2017-10-22 23:39:44
Document Index: 228004718

Matched Legal Cases: ['art 512', 'art 511', 'art 521', 'art 512', 'art 512', 'art 511']

Patent US7859185 - Light-emitting device - Google Patents
A light-emitting device comprising a solid-state light source (3), at least one conversion element (4) and a light-scattering element (6), wherein the solid-state light source (3) is provided to emit a first part (511) of a primary radiation for entry into the light-scattering element (6) and a second...http://www.google.com/patents/US7859185?utm_source=gb-gplus-sharePatent US7859185 - Light-emitting device
Publication number US7859185 B2
Application number US 12/162,072
PCT number PCT/IB2007/050112
Also published as CN101375420A, CN101375420B, EP1979954A1, EP1979954B1, US20090026908, WO2007085977A1
Publication number 12162072, 162072, PCT/2007/50112, PCT/IB/2007/050112, PCT/IB/2007/50112, PCT/IB/7/050112, PCT/IB/7/50112, PCT/IB2007/050112, PCT/IB2007/50112, PCT/IB2007050112, PCT/IB200750112, PCT/IB7/050112, PCT/IB7/50112, PCT/IB7050112, PCT/IB750112, US 7859185 B2, US 7859185B2, US-B2-7859185, US7859185 B2, US7859185B2
Inventors Hans-Helmut Bechtel, Wolfgang Busselt, Peter Schmidt
Patent Citations (10), Non-Patent Citations (1), Referenced by (3), Classifications (29), Legal Events (2)
US 7859185 B2
12. A light-emitting device as claimed in claim 10, characterized in that the particles comprise materials from the group of pigments for absorbing primary and or secondary radiation and subsequent re-emission at a different wavelength.
In an embodiment, the conversion element 4 may comprise a pressed ceramic material of essentially light-converting phosphor material or a dimensionally stable matrix material, for example, PMMA or other materials that can be doped with particles and have embedded light-converting particles. In another embodiment, the conversion element 4 comprises a ceramic material having a density of more than 97% of the theoretical solid-state density. Due to the small intrinsic scattering effect, such a conversion element 4 emits a larger portion 521 of the secondary radiation perpendicularly to the average direction of propagation of the second part 512 of the primary radiation. This leads to a better miscibility of the first part 511 of the primary radiation with the laterally exiting secondary radiation 521. Additionally, the small scattering effect reduces the average length of the optical path for the second part 521 of the primary radiation in the conversion element 4 up to the exit from the conversion element. Thus, the portion of the radiationless re-absorption of the second part 512 of the primary radiation in the conversion element is reduced and, consequently, the efficiency of the light-emitting device is further increased. The scattering effect is obtained by means of special sintering methods, for example, by sintering the ceramic material under reducing conditions at 1700 to 1750° C. for 2 to 8 hours, which results in materials having a density >96% of the theoretical density without porosity, and by subsequently sintering the material at 1750° C. under argon gas pressure (0.500 kbar to 2 kbar) for 10 hours in order to remove residual porosities. In such ceramics for light conversion, the secondary radiation comprises a clearly higher portion of secondary radiation 521, which exits laterally from the conversion element (thus from the surface of the conversion element, whose layer normal is essentially at right angles to the direction of propagation of the second part 512 of the primary radiation), as compared with ceramics of pressed phosphor powder.
FIG. 2 and FIG. 3 show the dimensions of the light-emitting device of FIG. 1, shown here without the light-scattering element 6 for the sake of better clarity, in a side elevation (FIG. 2) and a plan view (FIG. 3), in a plane of intersection A-B. The solid-state light source 3 has a surface of 1 mm×1 mm and is hatched for the sake of a better representation, although it is arranged below the conversion element 4 in the plan view and thus not directly visible in the plan view. The conversion element 4 projects above the solid-state light source 3 perpendicularly to the average direction of propagation of light 5 by 0.08 mm in the X1 and X3 directions, respectively, and by 0.15 mm in the X2 and X4 directions, respectively.
Despite this projection, the solid-state light source 3 emits a noticeable first part 511 of primary radiation, which is perceivable by several thousand Kelvin, as shown in FIG. 4, in viewing angle-dependent measurements of the correlated color temperature without using a light-scattering element by shifting the correlated color temperature between small and large viewing angles. The curves in FIG. 4 represent angle-dependent measurements in the four directions denoted as X1 to X4 in FIG. 3. Therein, a viewing angle of 0° corresponds to a perpendicular plan view of the light-emitting device. Radiation in the blue or yellow spectral range was used as primary and secondary radiation. In the plan view, white mixed light with a color temperature in the range of 4700 Kelvin resulted, while the color temperature of the white light is up to 8000 Kelvin at large viewing angles and thus comprises a high portion of blue primary radiation.
In a geometry of the light-emitting device selected according to FIG. 1, a blue emitting LED with a maximum emission at 450 nm and a YAG:Ce ceramic material applied on the solid-state light source were used as a solid-state light source for producing yellow secondary radiation from a ceramic material having a density of 98% of the theoretical solid-state density. The ceramic disk had a thickness of 250 μm. The raw material of the ceramic disk was manufactured by 12 hours of grinding 40 g of Y2O3, 32 g of Al2O3 and 3.44 g of CeO2 in isopropanol by means of 1.5 kg of Al2O3 grinding balls, and subsequent burning of the dried powder at 1300° C. in a CO atmosphere. The YAG:Ce powder obtained was deagglomerated in ethyl alcohol by means of a planet ball mill having agate-grinding cups, and subsequently ceramic green bodies (diameter 100 mm, height 2 mm) were manufactured by means of slip casting in plaster molds. After drying, the green bodies were burned on graphite disks in a CO atmosphere at 1700° for two hours. Subsequently, the YAG ceramic aterial was sawn to 290 μm, surface-ground and polished. The density of the ceramic material is 98% of the theoretical density. The necessary ceramic disks are then cut out with a laser and cleaned. The transmission of the ceramic material was 80% at a wavelength of 600 nm. Between the ceramic disk and the LED there was a thin layer of silicon gel having a thickness smaller than 10 μm of the firm of Gelest Inc PP2-D200 Gelest gel D200 for optically coupling the ceramic disk to the solid-state light source. Subsequently, a spherical lens was fitted, whose gap 6 was filled with silicon gel including embedded light-scattering particles. In this embodiment, this filled gap 6 represents the light-scattering element 6. The particles embedded in the silicon gel comprised ZrO2 with an average particle diameter of 0.25 μm. The light distribution showed a 92% conformity with an ideal Lambertian distribution pattern and hence corresponds very well to a Lambertian distribution.
US20050194603 Jan 20, 2005 Sep 8, 2005 Slater David B.Jr. Light emitting diodes including barrier layers/sublayers and manufacturing methods therefor
1 Written Opinion; Applic. No. PCT/IB2007/050112.
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U.S. Classification 313/502, 313/506, 313/503, 313/498, 313/512
International Classification H01J63/04, H01L33/50, H01L33/54, H01J1/62, H01L33/58
Cooperative Classification C04B2235/652, C04B2235/3229, C04B35/44, C04B2235/658, C04B35/6268, C04B2235/9653, C04B2235/764, C04B35/6265, C04B2235/3225, H01L33/505, C09K11/7774, H01L33/54, H01L33/58, H01L33/508, H01L2933/0091, F21K9/00
European Classification C09K11/77S6, H01L33/58, H01L33/50C
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BECHTEL, HANS-HELMUT;BUSSELT, WOLFGANG;SCHMIDT, PETER;REEL/FRAME:021287/0614;SIGNING DATES FROM 20070119 TO 20070122
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BECHTEL, HANS-HELMUT;BUSSELT, WOLFGANG;SCHMIDT, PETER;SIGNING DATES FROM 20070119 TO 20070122;REEL/FRAME:021287/0614