For a long time, the reason why the light-emitting diode has not been used for illumination is that the light-emitting diode usually emits only red or yellow light, and in order to obtain white light, it must also produce a light-emitting diode capable of emitting Blu-ray. In this way, red, yellow, blue three light "mixed", it produces white light. The problem that puzzles people is finally solved. Scientists have discovered a new type of semiconductor material, gallium nitride, which emits blue light after proper treatment. When the problem of blue light is solved, the problem of whitish lights has hope. Fryes John, of the Department of Materials at the University of Cambridge, said they had developed a white light light-emitting diode bulb in the experiment, which emits light that is very close to the sun and has a good prospect for application. The light-emitting diode bulbs, he says, are made of semiconductors, therefore, the light-emitting device can be done very small, only a few millimeters, installed on the wall or ceiling, if not turn on the lights, almost unaware of their existence, so that the ordinary incandescent lamp should be equipped with a lampshade to prevent the rays of the eye. In addition, the lamp life is very long, installed after almost no replacement, people may forget to change the light bulb is what. He is calling on the UK government to increase investment to ensure that Britain is in the forefront of this technology. In addition to durability, this kind of lamp has great potential in energy saving. According to calculations, if half of the light bulbs in the United States use light-emitting diode bulbs, it can shut down 24 power stations, save billions of of dollars, carbon dioxide emissions will also be significantly reduced. Because of this, the United States has planned that by 2006, all traffic lights will use light-emitting diode bulbs, so each intersection can save 750 of dollars a year. Despite the benefits of the bulbs, there are two major hurdles to actually getting into the ordinary family. The price is too high, the price of each bulb is 30 pounds, and the ordinary incandescent light bulb only 35 pence, the gap is too big. Second, it is also difficult to produce a white light bulb suitable for family use.