LED with particles in encapsulant for increased light extraction and non-yellow off-state color
US7791093B2 · kind B2 · utility
Assignees
Inventors
Key dates
| Filing date | Sep 4, 2007 |
| Grant date | Sep 7, 2010 |
| Priority date | — |
| Expiry date | Dec 29, 2028 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH10H20/882
Abstract
In one embodiment, sub-micron size granules of TiO2, ZrO2, or other white colored non-phosphor inert granules are mixed with a silicone encapsulant and applied over an LED. In one experiment, the granules increased the light output of a GaN LED more than 5% when the inert material was between about 2.5-5% by weight of the encapsulant. Generally, a percentage of the inert material greater than 5% begins to reduce the light output. If the LED has a yellowish YAG phosphor coating, the white granules in the encapsulant make the LED appear whiter when the LED is in an off state, which is a more pleasing color when the LED is used as a white light flash in small cameras. The addition of the granules also reduces the variation of color temperature over the view angle and position over the LED, which is important for a camera flash and projection applications.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.