July 27, according to Hong Kong Ta Kung Network reported that Hong Kong can be said that one of the brightest city in the world, a lot of energy spent in the general lighting and advertising and decorative lighting. In recent years, various sectors of the local community has become increasingly concerned about the energy efficiency and related environmental issues, businesses and individuals to participate in "Earth Hour" global energy-saving activities are also beginning to see enthusiastic visible development of environmentally friendly lighting is the trend. New lighting technology Light-emitting diode (LED) is certainly a favorite of environmentalists. LED is not only extremely longevity and rugged, small volume, switch quickly developed from the LED lighting technology with high energy efficiency, more importantly, LED lighting is very low CO2 emissions. In addition, LED saving light bulbs, it does not contain mercury, discarded as general waste disposal will not cause particular damage to the environment; mention longevity tenfold than saving light bulbs. Thus, LED is the best choice for environmentally friendly lighting. LED bulbs lit by the movement of electrons, its light is not so magnificent, and thus does not glare. LED lights to light up to rely on the LED drive, this drive is a light bulb to provide a stable and reliable power supply, the LED light is more effective, and can be compatible with other lighting devices, drives, LED lights can be used anywhere even directly replace existing halogen bulbs used. LED lighting technology of the Hong Kong Applied Science and Technology Research Institute has developed, can contribute to promote environmentally friendly lighting Tim. At present, the group ASTRI integrated circuit such as MR16 LED light bulbs and other lighting facilities, developed a small LED driver, this technology has been successfully transferred to industry. Expected over the next few years, the market demand for LED lighting products for multiples rise. LED lamp current can be adjusted by two control ─ pulse width modulation (PWM) and pulse frequency modulation (PFM). PWM control method is a control algorithm by the control signal is modulated into a pulse signal of the duty cycle (i.e., the positive pulse duration and pulse the ratio of the total cycle) As a result of this pulse signal is a fixed frequency signal at a specific frequency with a strong energy may affect other electronic devices. On the other hand, in the PFM control mode, the control signal is modulated into a pulse frequency of the signal, its energy and thus dispersed in a broad spectrum, does not pose a threat to the surrounding devices.