US Patent 7495383 - Phosphor coated with quantum dots

http://www.freepatentsonline.com/7495383.html

One of the key advantages of quantum dots used in sensor and display applications is that the detection or emission wavelength can be tuned based on the particle size. However, using uniform size quantum dots in a colloidal system can result in too narrow a wavelength selectivity which is undesirable for some application such as a white light source. This patent from Avago Technologies teaches achieving a wider wavelength responsiveness by coating larger phosphor particles with the smaller quantum dots. Claim 1 reads:

1. A phosphor composition comprising:

first phosphor particles of a first size, said first phosphor particles of a first size converting light of an excitation wavelength to light having a first spectrum characterized by an intensity of light that varies as a function of wavelength, said first spectrum being independent of said size of said first phosphor particles; and

particles of a QD phosphor of a second size that convert light of said excitation wavelength to light having a QD phosphor spectrum characterized by an intensity of light that varies as a function of wavelength; wherein each of said first phosphor particles of a first size are coated with one or more of said particles of a QD phosphor of a second size.