Technical Field
The disclosure relates to a phosphor, and in particular it relates to an illumination device utilizing the same.
Description of the Related Art
There are many manufacturing methods for making white light-emitting diodes (WLEDs), such as (1) applying a yellow phosphor onto a blue light-emitting diode (LED) chip, (2) applying a red phosphor and a green phosphor powder to a blue LED chip, (3) mixing a red LED chip, a green LED chip, and a blue LED chip, and (4) applying a blue phosphor, a green phosphor, and a red phosphor (or different phosphor powders of different colors) onto an ultra-violet (UV) LED chip.
The WLED has several advantages over traditional incandescent light bulbs, such as long lifespan, low power consumption, small volume, fast response time, and good shake-resistance. As a result, it has gradually replaced traditional lighting products. However, current WLEDs still need to overcome problems in development, such as heat dissipation, insufficient brightness, and their relatively high price. In the lighting market, WLEDs are mainly used in auxiliary lighting such as flash lights, car interior lights, or decorative architectural lighting products. WLEDs are expected to replace traditional lighting products in the future to enter the mainstream of the global lighting market.
In addition to packaging techniques, the phosphor that is chosen is an important factor in the luminous efficiency of a light source. One of the directions of the research being conducted by photo electronic semiconductor companies and lighting companies is modifying phosphor compositions to increase phosphor conversion efficiency. The color render index of the white light generated by a yellow phosphor powder excited by a traditional single blue chip is not good, as the color saturation of an object illuminated by the white light is poor, thereby lowering its value in the commercial lighting market. Compared with this method, the application of a green phosphor and a red phosphor onto a blue LED may produce a white light with a better color render index. Accordingly, different phosphor compositions for use in a white light illumination device are called for.