Color-converting materials (e.g., phosphor materials) absorb light at certain wavelengths and emit light at different wavelengths. Optical components including color-converting materials are used in a variety of electronic devices, including illumination devices and devices with electronic displays, such as mobile phones, digital cameras, and televisions. In many such devices, color-converting materials are used in conjunction with solid-state radiation transducers (“SSRTs”). Examples of SSRTs include light-emitting diodes, organic light-emitting diodes, and polymer light-emitting diodes. In a common application, a color-converting material is used to modify the light output from an SSRT to include additional or different wavelengths. SSRTs typically emit light having a narrow range of wavelengths. Color-converting materials can absorb some or all of the emitted light from an SSRT and convert it into light having a different range of wavelengths. For example, some SSRT devices include an SSRT that emits blue light and a color-converting material that absorbs some of the blue light and converts it into yellow light. The combination of blue light from the SSRT and yellow light from the color-converting material can appear white. Known color-converting materials useful for this purpose include yttrium aluminum garnet (“YAG”) doped with various rare earth elements, such as cerium.
Optical components of SSRT devices can include particles of color-converting material within a matrix. Selecting the type of color-converting material and the size and concentration of the particles of color-converting material within the matrix can allow for significant control over the performance characteristics of the optical component. Optical components manufactured according to the same specifications, however, can have somewhat different performance characteristics. Other components of SSRT devices, such as the SSRTs themselves, also typically exhibit variable performance characteristics despite like manufacturing. Additionally, different SSRTs manufactured on the same wafer can have different performance characteristics. Certain applications require SSRT devices having performance characteristics falling within a specified range. Correlated color temperature (“CCT”) and lumen output are examples of performance characteristics commonly specified for SSRT devices. Product binning, which typically includes testing SSRT devices after manufacturing and separating the SSRT devices according to the test results, can be used to ensure that SSRT devices sold to customers meet specified requirements.
SSRT devices from the same manufacturing process can have significantly different market values depending on performance. Customers of SSRT devices often specify both non-performance characteristics (e.g., size) and performance characteristics (e.g., CCT). Non-performance characteristics can be easier to control during manufacturing than performance characteristics. Accordingly, it is typical for only some SSRT devices manufactured according to specified non-performance characteristics to also meet corresponding performance characteristics. SSRT devices not meeting specified performance characteristics can be discarded or sold at a substantial discount for use in other applications, such as low-end applications. The percentage of SSRT devices from a manufacturing process meeting specified performance characteristics can significantly affect the profitability of the manufacturing process. Accordingly, there is a need for innovation related to performance characteristics of SSRT devices and components of SSRT devices, such as to improve the percentage of SSRT devices from a manufacturing process meeting specified performance characteristics.
USPTO Backgrounds
USPTO Backgrounds