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LEDs with particles in encapsulant for increased light extraction and non-yellow off-state colors

A technology of encapsulants and granules, applied in the direction of electrical components, electrical solid devices, circuits, etc., can solve problems such as unattractiveness

Active Publication Date: 2018-07-17
LUMILEDS HLDG BV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This yellow-green color is usually unattractive and typically does not match the camera look very well

Method used

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  • LEDs with particles in encapsulant for increased light extraction and non-yellow off-state colors
  • LEDs with particles in encapsulant for increased light extraction and non-yellow off-state colors
  • LEDs with particles in encapsulant for increased light extraction and non-yellow off-state colors

Examples

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Embodiment Construction

[0022] Although the invention can be applied to any type of LED, a specific LED used in all examples will be described in detail. FIG. 1 is a cross-sectional view of a conventional white light LED 10 encapsulated in silicone.

[0023] The active layer of LED 10 in this example produces blue light. LED 10 is formed on a starting growth substrate such as sapphire, SiC or GaN. Typically, n-layer 12 is grown, followed by active layer 14 , followed by p-layer 16 . The p-layer 16 is etched to expose a portion of the underlying n-layer 12 . A reflective metal electrode 18 (eg, silver, aluminum or an alloy) is then formed over the surface of the LED, contacting the n- and p-layers. There may be many distributed electrodes to spread the current more evenly. When the diode is forward biased, the active layer 14 emits light at a wavelength determined by the composition of the active layer (eg AlInGaN). Forming such LEDs is well known and need not be described in more detail. Additi...

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Abstract

In one embodiment, TiO2, ZrO2 or submicron size particles (34) of other white non-phosphor inert particles and a silicone resin packaging agent (32) are mixed and applied to an LED (10). In one experiment, light output of the GaN LED is enabled to be increased for more than 5% by the particles when the inert material is about 2.5-5% of the packaging agent by weight. Usually, light output begins to reduce by the inert material of the percentage greater than 5%. If the LED has a light yellow YAG phosphor coating layer, the LED is enabled to look more white by the white particles in the packaging agent when the LED is in the off-state, and the color is a more pleasant color when the LED is used as a white flash lamp (42) in a small camera (40). Change of the visual angle and color temperature of the position of the LED can also be reduced through increasing of the particles so as to be important for the application of the camera flash lamp and projection.

Description

[0001] This application is a divisional application with the application number 200880131373.5, the filing date is October 1, 2008, and the title of the invention is "LED with particles in encapsulant for increased light extraction and non-yellow off-state color" Application. technical field [0002] The present invention relates to light emitting diodes (LEDs), and in particular to techniques for improving light extraction. The invention also relates to forming a non-yellow off-state color of an LED having a light yellow phosphor coating. Background technique [0003] Semiconductor LEDs such as GaN LEDs have a much higher refractive index (eg, n=2.2-3.0 for GaN) than that of air (n = approximately 1). By encapsulating the LED in a transparent material with an intermediate refractive index such as silicone (n=1.4-1.76), light extraction is significantly improved. The encapsulant also protects the semiconductor LED die. It is desirable to further increase light extraction....

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01L33/50H01L33/56
CPCH01L33/50H01L33/56H01L2224/16225
Inventor G.巴辛A.S.哈奎C.陈R.S.韦斯特P.马丁
Owner LUMILEDS HLDG BV