Dimming LED lighting solutions and market growth potential

Today, LED lighting has verily become a mainstream technology. The technology is maturing, one of the signs that a large number of LED lighting standards and norms have been put forward. Stringent efficiency requirements already exist for quite some time and will continue to improve. But Recently, LED lighting designer's work is more difficult, because it will also meet the following two requirements: either to use dimmers for incandescent dimming control to achieve, but also to achieve high power factor performance for LED brightness adjustment, currently divided into analog dimming and PWM dimming, the following LED dimming will be introduced the relevant situation.

Dimming lighting systems are very common features. For the incandescent lamp, it can be easily achieved at low cost. LED lights are dimming there is a certain degree of difficulty, but for architects and residential users, the transition to LED lighting, dimming may not want to lose control due advantage. This involves a lot of class LED lighting knowledge.

Power factor is a very important factor, because of the high power factor can reduce the loss of distribution network. Reduce electricity use impact on the environment is the most effective way to reduce waste and therefore regulatory agencies around the world, they are more stringent power factor specifications. One example is the solid-state lighting Energy Star guidelines for energy efficiency (09/12/07), which provides residential lighting products, power factor (PF) should be greater than 0.7, the commercial lighting products, power factor (PF) should be greater than 0.9.

LED lamps dimming method most common, there are three, these three skills are dimming LED drive current based on the change of the input for dimming. According to different circuit systems can be divided into the dimming and PWM dimming to imitate.

The first: This dimming method is through modulation of the LED drive current to complete the LED lights dimming the brightness of the LED chip and the LED drive current into a certain proportion of stakeholders, so we can adjust the LED drive current to control the LED lights light and shade.

The second: This method is called to imitate dimming dimming dimming method or linear methods. This kind of approach has the advantage of dimming: When the drive current linear growth or decreased, reducing the drive current overshoot during the course of life of LED chips, and the dimming circuit strong anti-nuisance. The flaw is the size of the drive current changes in the process is definitely the color temperature of LED chips have a certain impact.

Third: This dimming method is called pulse width modulation (PWM). After the method is to adjust the drive current was square wave, the pulse width variable, through the modulation of pulse width modulated LED light into a continuous light of the time, and also change the input power to reach the energy saving, dimming objectives. Probably with the usual frequency of 200Hz ~ 10KHz; because the human eye visual lag, do not feel in the dimming light generated in the process shining phenomenon. This method has the advantage of dimming LED's thermal performance can improve the defect is the driving current overshoot on the life of LED chip must have some effect.

Overall, the analog dimming is usually very simple to achieve. However, due to the characteristics of LED light to the average drive current and offset. For monochromatic LED, its dominant wavelength will change. The white LED, the correlated color temperature (CCT) will change. PWM dimming is used to ensure that the designers need to send the color of LED. PWM dimming can increase the output current accuracy. Linear analog dimming adjustment will reduce the output current accuracy. In general, relative to the analog dimming, PWM dimming control for precision than the linear light output.