Object-oriented emission-adaptive phosphor layer for pc-white LED

摘要

The emission-adaptive phosphor layer was fabricated by self-exposure method to realize the pc-white LED. The effect of phosphor layer forming parameters such as phosphor content, exposure intensity and exposure time on the phosphor layer shape and LED characteristics was investigated. Through the fabrication process of phosphor layer, two types of phosphor layer shape were fabricated by phosphor layer forming parameters. In the case of low exposure intensity and/or short exposure time with high phosphor content, the conformal coating shape phosphor layer which is imitative of the irradiance pattern of an LED chip was formed, whereas in the high exposure intensity and/or long exposure time with low phosphor content, the light distribution proportional shape phosphor layer which reflects the near-filed pattern of an LED chip was formed. Therefore the latter was superior to the former in the angular color homogeneity due to a strong similarity between the phosphor content distribution and the light intensity distribution of an LED chip in all directions. It was concluded that the object-oriented emission-adaptive phosphor layer closely similar to the light distribution proportional shape phosphor layer was formed in the condition of high exposure intensity and/or long exposure time with high phosphor content and resulted in high luminous efficacy, low correlated color temperature as well as high angular color homogeneity.