LED light-emitting principle (2)

In 1968, LED’s have made breakthroughs in research and development, the use of nitrogen-doped GaAsP technology to achieve the efficiency of the device 1 lm / W, and the ability to glow red, orange light and yellow light. By 1971, the industry has introduced with the same efficiency GaP green die LED. 1972, a small number of LED displays for watches and calculators. World’s first LED watch was originally sold in expensive jewelry stores, and its price is as high as 2,100 dollars. Almost at the same time, Hewlett-Packard and Texas Instruments also introduced a 7-segment red LED display with a calculator. 70 to the 20th century, due to LED devices in the home and office equipment in the large number of applications, LED prices plummet. In fact, LED is the main figures of that era and text display. However, in many commercial devices, LED displays also came from the fierce competition of other display technologies such as LCD,Led Torch, plasma and vacuum fluorescent tube display.