High brightness LED technology and application trends

Reflective high brightness LED LED LCD projector change

In recent years, the TV market has gradually transformed into a digital TV, pre cast TV, rear projection TV category of large TV market. This kind of light source projection TV display using the exception are the ultra high pressure mercury lamp, high pressure mercury vapor lamps in the lighting, in order to put the steam pressure control in about 200 atmospheres and the use of a large number of mercury. As everyone knows, mercury is of great harm, to prevent pollution, avoid the use of mercury, its development is currently looking for alternatives to a lot of research, but Mercury is a necessary condition to ensure the lighting power, it is difficult to find other convenient and suitable alternatives.

However, the current increases caused by the consumption of electrode with lighting, high voltage and high cost, the service life of the lamp and other problems have to be solved at present not only inert gas lamp mercury lamp, electrodeless lamp and microwave lighting type. On the other hand, since 2000, because of the power of LED to improve, it as a small halogen lamp alternative light source has attracted the attention of the world.

2006 - CES exhibition with LED on the LCD projector light source was first published at the beginning of 2006, a light emitting diode for liquid crystal projector light source have been published, since instead of the traditional super high pressure mercury lamp R (red), G (green), B (blue) color emitting two polar body (LED) as the light source, the industry has actively designed small and battery powered front projection type liquid crystal projector, and using light emitting diode as a projection type liquid crystal projector light source, color range is beyond 100% NTSC. In January 2006, held in Las Vegas, "CES 2006", the use of LED for liquid crystal projector light source for the first time publicly, therefore, the industry has been in a secret before the state of research and development, and then gradually open to the market development of the light emitting diode light source projection type liquid crystal projector. In addition, in order to develop more distinctive products, with semiconductor laser for liquid crystal projector light source, is also active in research and development, it is foreseeable that with the changing light source, liquid crystal projector will also be of great change. In fact, because the light emitting diode has many advantages, the use of LED for liquid crystal projector light source of the idea, from long ago have begun to put into development, for example, can achieve the miniaturization, battery powered, expand the color range of performance characteristics and long service life etc.. The traditional, LCD projector is the use of ultra high pressure mercury lamp as the light source, but due to ultra high pressure mercury lamp start, high-pressure 10KV (lighting several moments will reach hundreds of KV), therefore, the bulb temperature also reaches 800 DEG to 900 DEG C, in such a high consumption of motor structure, it you must use the AC (AC) drive power, and the power circuit is complex and the necessary cooling solution. And because of ultra high pressure mercury lamp and fluorescent lamp light-emitting principle is the same, so rely on mercury to produce ultraviolet light and emit light excitation light source, so from the start of lighting, reach a certain brightness too need a certain starting time, and after use after turning off the heat, also need to take a long time to reach the cooling state. Because of such a variety of inconvenience, LCD projector related industry will need to find a new light source to replace the ultra-high pressure mercury lamp. - to LED as the light source can greatly improve the performance of the current market mainstream LCD projector, the ultra high pressure mercury lamp of white light, especially is separated into three RGB color gamut, in order to achieve high performance, but, if you can, can put the red green and blue three colors, using direct light source components only is the future trend of development. The LCD projector manufacturers invest a lot of energy to the development of LED LCD projector, because the light emitting diode as a light source, can have a substantial performance improvement space. In the past, the luminous efficiency and luminous flux of LED is not very enough, do not have the LCD projector light source performance. However, in recent years, with the performance of a substantial increase, the industry believes that LED has been able to become a liquid crystal projector light source characteristics, started the actual research and development. However, in practical applications, it is not difficult to find that the use of LED in front projection LCD projector and rear projection LCD projector is not the same. Rear projection LED LCD projector projection performance, although it can not be said to have reached the same level as the rear projection ultra-high pressure mercury liquid crystal projector, but basically, the same brightness. On the other hand, because the application is expected to act as a small, front projection LED LCD projector in brightness of the obstacles is relatively small, also do not need to reduce the heat dissipation device and the optical system and the trouble of mechanism design, so it is easy to maintain the brightness required.

The comparison of general high power LED and the reflection type LED heat dissipation. (drawing: Lu Qingru)

Although there are such advantages, but the relative brightness, front projection type LED LCD projector, and a front projection type ultra-high pressure mercury lamp is much worse than the LCD projector, brightness can be projected only 10 to 20 lumens, such as brightness impossible front projection type ultra high pressure water silver lamps of LCD projector so, in the bright conference room can also be put in clear image zoom in to 30 to 40 inches. Most of the LCD projector producers for the pre cast LED LCD projector sales model and the prospects are a certain degree of difficulty, although the front projection LED LCD projector is the demand for small size, and