A new direct thermal full color recording system named “TA” (Thermo Autochrome) has been developed. The TA system creates high quality continuous tone full color prints without any accompanying wastes such as an ink ribbon or an ink cartridge. In addition, the color image remains stable when coming in contact with oil and plasticizer. This is because the color image of TA paper is formed within the microcapsule directly on the base paper with no transfer of coloring agents. In this paper we will describe the light stability improvement technology for TA paper. Cutting ultraviolet light by introducing an ultraviolet absorber precursor layer which forms an ultraviolet absorber by light exposure on the color forming layer is effective. Cutting oxygen by adding a low oxygen permeability layer between the color forming layer and the basepaper is also effective in improving light stability. Utilizing these two technologies, we have succeeded in developing a new type of TA paper which has superior light stability . Introduction Recently we have developed a new direct thermal full color recording system named “TA” (Thermo Autochrome) that can produce prints comparable to D2T2 in image quality. TA paper consists of a base paper coated with cyan, magenta and yellow color forming layers. Because TA paper synthesizes color itself, the TA system needs no ink ribbon, ink cartridge or other disposable supplies. However, at the same time this characteristic of TA paper is a cause of inferior light stability especially in the background coloration. We will describe a new technology in TA paper that greatly enhances its light stability. Mechanism of Image Formation A simplified cross-sectional view of the TA paper is shown in Figure 1. The outermost layer is a heat-resistant protective layer. The yellow color forming layer is comprised of a microencapsulated diazonium salt compound, an organic base, and a coupler which react to form a yellow azo dye. The magenta color forming layer is comprised of a microencapsulated diazonium salt compound, an organic base, and a coupler which react to form a magenta azo dye. The innermost color forming layer is comprised of a basic leuco dye and a phenolic compound developer which react to form a cyan dye. 10 Yellow Layer(Diazo+Coupler) Magenta Layer(Diazo+Coupler) Cyan Layer (Basic Leuco dye + Phenolic Compound) Heat-resistant Protective Layer