In the 1970s, the earliest GaP and GaAsP homo-junction LEDs with low luminous efficiency in red, yellow, and green colors started to be used for indicator lights, numerical and text displays. From then on, LEDs began to enter various application fields, including aerospace, aircraft, automobiles, industrial applications, communications, consumer products, etc., covering all sectors of the national economy and reaching every household. By 1996, the global sales of LEDs had reached several billion US dollars. Despite being restricted by color and luminous efficiency for many years, GaP and GaAsP LEDs have always been favored by users due to their long lifespan, high reliability, low operating current, and compatibility with TTL and CMOS digital circuits. In the past decade, high brightness and full-color have always been the cutting-edge research topics in LED materials and device processes. Ultra-high brightness (UHB) refers to LEDs with a luminous intensity that reaches or exceeds 100 mcd, also known as candela (cd) level LEDs. The development progress of high-brightness AlGaInP and InGaN LEDs has been very rapid, now achieving performance levels that conventional materials such as GaAlAs, GaAsP, and GaP cannot reach. In 1991, Japan's Toshiba Corporation and America's HP Company developed InGaAlP 620nm orange ultra-high brightness LEDs. In 1992, practical InGaAlP 590nm yellow ultra-high brightness LEDs were realized. In the same year, Toshiba Corporation developed InGaAlP 573nm yellow-green ultra-high brightness LEDs with a normal light intensity of 2cd. In 1994, Japan's Nichia Corporation developed InGaN 450nm blue (green) ultra-high brightness LEDs. By this point, the three primary colors required for color display—red, green, blue—as well as multiple colors such as orange and yellow LEDs, had all achieved candela-level luminous intensity, realizing ultra-high brightness and full-color capabilities, making outdoor full-color displays with light-emitting tubes a reality. China's development of LEDs started in the 1970s, and the industry emerged in the 1980s. There are approximately 100 enterprises nationwide, with 95% of manufacturers engaged in downstream packaging production, and almost all required chip cores are imported from abroad. Through technical renovations and breakthroughs during several "five-year plans," as well as the introduction of advanced foreign equipment and some key technologies, China's LED production technology has taken a step forward.